Litigating Substantial Similarity in a Copyright Case: A Practical Guide

Summary. This guide walks plaintiffs and defendants through a copyright case in which the decisive question is whether two works are substantially similar in protectable expression, in the order the case actually unfolds. It begins with pre-suit assessment, registration and deposit-copy checks, and the similarity chart and filtration analysis that every later stage relies on. It then explains how to plead similarity and attack it on a motion to dismiss, how to use the scheduling conference to shape discovery, how to take the access and creation discovery that proves or disproves copying, and how to retain, disclose, and defend experts under Rule 702. Later steps cover summary judgment in the major circuits, jury instructions and verdict forms, presenting the works at trial, preserving Rule 50 and Rule 51 objections, appeals, and the fee and cost rules that drive settlement. A worked example follows a small game studio's clone case from discovery of the copying through mediation, and the guide closes with common mistakes, an FAQ, and practical takeaways.

A surprising number of copyright cases about look-alike works are decided by procedure rather than by anyone's eyes or ears. Plaintiffs lose them in the first ninety days by suing on a pending application, attaching the wrong version of the work, or answering a motion to dismiss with forty "similarities" that turn out to be ideas. Either side can lose them in the last ninety minutes of trial: in the "Blurred Lines" case, neither side moved for judgment as a matter of law before the jury retired, and the Ninth Circuit held that the omission left no one, including the court of appeals, able to set the verdict aside on that ground.

This guide follows a substantial similarity case in the order it actually happens, step by step, for the side bringing it and the side defending it. For the doctrine behind each step (access, probative similarity, the circuit tests, the filtration doctrines, and the leading music, literary, visual, and software decisions), read the companion article, Proving Copyright Infringement: Access, Substantial Similarity, and the Tests Courts Actually Use. To screen a claim quickly, use the Copyright Infringement Claim Evaluation Checklist: A Practical Checklist. For fill-in similarity charts, expert report outlines, and filtration templates, use the Copyright Infringement Litigation Toolkit: Similarity Charts, Expert Reports, and Filtration Analyses.

The short answer

• The case is a fight about filtration. Substantial similarity means similarity in protectable expression, so the side that wins the argument about what is protectable (and what is an idea, a fact, a genre convention, public domain material, or someone else's work) usually wins the case. Build that analysis before you file or answer, and keep refining it.
• Get into court correctly. A United States work needs a registration decision before suit under 17 U.S.C. § 411(a) and Fourth Estate Public Benefit Corp. v. Wall-Street.com, LLC, 586 U.S. 296 (2019); statutory damages and fees depend on registration timing under 17 U.S.C. § 412; and the registered version, or for older works the deposit copy, defines what the jury compares.
• Put the works in front of the judge early. Courts compare the works themselves on a motion to dismiss when nothing else would matter, as in Peter F. Gaito Architecture, LLC v. Simone Development Corp., 602 F.3d 57 (2d Cir. 2010) and Rentmeester v. Nike, Inc., 883 F.3d 1111 (9th Cir. 2018), and refuse when expert analysis or discovery could change the answer.
• Shape the schedule. Use the Fed. R. Civ. P. 16 conference to force an early exchange of the works, an identification of the elements the plaintiff claims, a protective order, and a sensible expert schedule.
• Discovery is about two stories. The plaintiff needs the access chain; the defendant needs its own creation record and the plaintiff's sources. Requests for admission and preservation failures end more cases than most lawyers expect.
• Experts are admissible only for what the step and the circuit allow, and Fed. R. Evid. 702 now demands a reliable method reliably applied. A ghost-written or unfiltered report can end a case on its own.
• Summary judgment is common, not rare. In the Ninth Circuit it is a fight over the extrinsic test; in the Second and Eleventh Circuits courts compare the works and grant judgment either way when no reasonable jury could differ.
• Trials are won and lost on instructions and preservation. Request and object to instructions on the record under Fed. R. Civ. P. 51, use a special verdict form, and move under Fed. R. Civ. P. 50 before the case goes to the jury.
• Fees cut both ways. Under 17 U.S.C. § 505, a losing plaintiff with an objectively unreasonable claim can pay the defendant's fees, and a late-registered plaintiff may be unable to recover its own.

The legal framework and the procedural map

The statute supplies the rights and the remedies and almost nothing about how similarity is proved. 17 U.S.C. § 106 lists the exclusive rights; 17 U.S.C. § 501 makes violating them infringement and lets the legal or beneficial owner sue; 17 U.S.C. § 102 excludes ideas, procedures, systems, and methods of operation in subsection (b); and 17 U.S.C. § 103 limits a compilation or derivative work to the material the author contributed. The registration provisions (17 U.S.C. § 410(c), § 411, and § 412) control who can sue, with what presumptions, and for which remedies. Federal courts have exclusive jurisdiction under 28 U.S.C. § 1338(a), and venue lies where the defendant "resides or may be found" under 28 U.S.C. § 1400(a). Everything else (access, probative similarity, the ordinary observer, the extrinsic and intrinsic tests, abstraction-filtration-comparison) is judge-made, which is why the procedural rules carry so much weight. The leading treatment remains 4 Melville B. Nimmer & David Nimmer, Nimmer on Copyright § 13.03, and the best short critique of the whole apparatus is Mark A. Lemley, Our Bizarre System for Proving Copyright Infringement, 57 J. Copyright Soc'y U.S.A. 719 (2010).

Here is how a contested similarity case moves through federal court, with typical timing for a case that does not settle early.

Two features of this map deserve emphasis. First, the judge decides far more than the "question of fact" label suggests: protectability, the extrinsic test in the Ninth Circuit, and the whole case whenever no reasonable jury could disagree. Second, nearly every stage has a preservation trap that converts a merits argument into a forfeited one. The steps below take them in order.

Step 1: Assess the claim before anyone files

For the copyright owner: four questions before the complaint

1. Can you sue at all? Confirm that the work is registered, or that the Copyright Office has refused registration, because Fourth Estate holds that registration is "made" only when the Office acts, and a suit filed on a pending application will be dismissed. If there is no registration, file one now and request special handling, the Office's expedited service, which it grants for pending or prospective litigation, customs matters, and contract or publishing deadlines (U.S. Copyright Office, Compendium of U.S. Copyright Office Practices § 623 (3d ed.); Circular 10). The surcharge is set in 37 C.F.R. § 201.3 and has long been $800 per claim; the payoff is a decision in days rather than months. Then check four details that later become motions:

• The version. Register, or confirm you registered, the version the defendant could actually have seen. A registration for version 1.0 does not cover expression first added in version 1.2, and a plaintiff who cannot put the registered version into evidence may have nothing to compare, as the software company in Airframe Systems, Inc. v. L-3 Communications Corp., 658 F.3d 100 (1st Cir. 2011) learned.
• The deposit. For works registered under the 1909 Act, the deposit copy defines the work, which is why the juries in Skidmore v. Led Zeppelin, 952 F.3d 1051 (9th Cir. 2020) (en banc) and Williams v. Gaye, 895 F.3d 1106 (9th Cir. 2018) never heard the famous recordings; they heard renditions limited to what the deposit copy showed. Order certified copies of the deposit and the application file early. The Office reproduces deposits for an attorney in actual or prospective litigation who submits its Litigation Statement form under 37 C.F.R. § 201.2(d), and that statement must be true: in Atari Games Corp. v. Nintendo of America Inc., 975 F.2d 832 (Fed. Cir. 1992), Atari's misrepresentation to obtain Nintendo's source code deposit helped sink its fair use defense.
• The timing. Compare the registration date with the date infringement began. Under § 412, statutory damages and fees are unavailable for infringement that started before registration unless the work was registered within three months of first publication. A certificate issued within five years of publication is prima facie evidence of validity under § 410(c).
• The chain of title. If the plaintiff is not the author, find the signed writing 17 U.S.C. § 204(a) requires, and the work-for-hire or assignment language behind it. See Copyright Ownership, Joint Authorship, and Termination of Transfers.

Finally, check limitations. The three-year period in 17 U.S.C. § 507(b) runs separately for each infringing act under Petrella v. Metro-Goldwyn-Mayer, Inc., 572 U.S. 663 (2014), and where the discovery rule applies, Warner Chappell Music, Inc. v. Nealy, 601 U.S. 366 (2024) allows damages for older infringement within a timely claim.

2. Can you prove copying in fact? Write the access story as a dated chain of names: who received the work, when, from whom, and how that person connects to the people who made the accused work. Look hard for direct evidence (an admission, a shared error, a file name, a metadata trail). If the chain is thin, ask whether the similarity is striking enough to stand on its own, and remember that the Ninth Circuit no longer lets strong access lower the similarity threshold after Skidmore.

3. What survives filtration? Build the first-pass comparison chart described in Step 2 before you decide anything else. If every row on the chart is an idea, a fact, or a convention of the genre, the claim is weak no matter how similar the works feel.

4. What is the case worth, and what could it cost you? Price the realistic remedy (lost license fees, the defendant's apportioned profits, or statutory damages if § 412 allows them) against the cost of litigating through summary judgment and the risk of paying the defendant's fees. Rule 11 applies with full force: in Christian v. Mattel, Inc., 286 F.3d 1118 (9th Cir. 2002), the Ninth Circuit upheld the finding that a complaint was frivolous where a reasonable pre-filing inquiry would have shown that the accused Barbie sculptures predated the plaintiff's doll and bore visible copyright notices. And ask whether you need a similarity fight at all. Where the defendant reproduced or performed the work itself, substantial similarity is beside the point; Range Road Music, Inc. v. East Coast Foods, Inc., 668 F.3d 1148 (9th Cir. 2012) affirmed summary judgment for music publishers whose investigator simply identified the songs a restaurant played.

For the accused: the first two weeks

1. Preserve. Send a written litigation hold the day the demand arrives, covering drafts, sketches, session files, design documents, chat channels, and version control. The creation record is the independent creation defense, and losing it invites sanctions under Fed. R. Civ. P. 37(e). See Litigation Holds, Spoliation, and Rule 37(e): Preserving Electronic Evidence Before It Costs You the Case.
2. Tender to your insurer. Some commercial general liability and media policies cover copyright claims, often limited to infringement in advertising, and late notice can forfeit coverage. Read the policy and tender promptly.
3. Interview the creators and map your sources. Who made the accused work, when, and from what? A shared ancestor (a public domain melody, a stock asset, a genre convention, an open source library) is the most effective answer to an inference of copying.
4. Test the plaintiff's paper. Pull the registration record. Ask whether the registration covers the version in suit, whether the claimant owns it, and whether the application contained a knowing inaccuracy that could invalidate it under 17 U.S.C. § 411(b) as construed in Unicolors, Inc. v. H&M Hennes & Mauritz, L.P., 595 U.S. 178 (2022), which requires actual knowledge (or willful blindness) of the inaccuracy and requires the court to ask the Register whether it would have mattered.
5. Measure exposure honestly. If § 412 bars statutory damages and fees, the realistic exposure is actual damages and apportioned profits, which changes the settlement math and the fee leverage.
6. Decide how to respond. Answer the letter in a way that preserves your defenses without educating the other side, and label settlement discussions under Fed. R. Evid. 408. If litigation is inevitable and the forum matters, consider suing first for a declaratory judgment under 28 U.S.C. § 2201. See Responding to a Cease and Desist Letter: A Practical Guide and Filing or Defending a Declaratory Judgment Action: A Practical Guide. If the claim arrives as a Copyright Claims Board notice instead, the decision is whether to opt out within 60 days; see Bringing or Defending a Claim Before the Copyright Claims Board: A Practical Guide.

Step 2: Build the comparison the whole case will be fought over

The most useful document in a similarity case is a disciplined comparison chart. It starts as privileged work product, prepared by counsel with a consulting expert whose views are generally shielded from discovery under Fed. R. Civ. P. 26(b)(4)(D), and it later becomes the complaint's exhibit, the spine of the expert report, the statement of facts at summary judgment, and the jury's demonstrative. Both sides need one. The plaintiff's version shows what was taken; the defendant's version shows why none of it counts.

What each row should contain

1. Pinpoints in both works. Page and line, measure and beat, timestamp, file and line number, or image layer. Vague rows ("both feature a lonely hero") are worthless.
2. The kind of similarity. Literal (verbatim text, identical code, traced lines), near-literal (paraphrase, a transposed melody, a recolored image), structural (sequence of events, program architecture, room layout), or overall impression.
3. The protectability call, with the reason. Idea or concept; fact or historical event; scènes à faire (stock elements of the genre); merger (the idea can be expressed only a few ways); external or functional constraint; public domain; third-party or licensed material; the plaintiff's own earlier work; or material generated by AI without human authorship.
4. Prior art. Earlier works sharing the element, with dates and sources. This column wins more motions than any other.
5. Significance. How important the element is to each work. A defendant cannot escape by pointing to how much it did not take, but a plaintiff cannot win by stacking trivia.
6. Differences. What the defendant changed, added, or omitted, because courts look at the works as wholes as well as row by row.

Lists that lose

Courts distrust long lists of scattered resemblances. The Ninth Circuit called such lists "inherently subjective and unreliable" in Litchfield v. Spielberg, 736 F.2d 1352 (9th Cir. 1984), affirming summary judgment that "E.T." did not infringe a musical play, and it was "particularly cautious" where the list emphasized random similarities scattered throughout the works. In Zella v. E.W. Scripps Co., 529 F. Supp. 2d 1124 (C.D. Cal. 2007), a court dismissed a claim against a television cooking show after taking judicial notice that a host, celebrity guests, interviews, and cooking are generic features of the genre. The plaintiff's answer is a pattern, not a pile: Metcalf v. Bochco, 294 F.3d 1069 (9th Cir. 2002) held that the particular sequence in which an author strings together a significant number of unprotectable elements can itself be protectable, but Skidmore and Gray v. Hudson, 28 F.4th 87 (9th Cir. 2022) require that theory to be stated concretely: which elements, arranged how, and why the arrangement is original.

Decide early which theory you are proving, because they need different evidence. Nimmer distinguishes fragmented literal similarity (copying of specific passages, weighed for quantity and quality) from comprehensive nonliteral similarity (copying of a work's fundamental structure or essence). 4 Nimmer on Copyright § 13.03[A][1]-[2]; see also Pamela Samuelson, A Fresh Look at Tests for Nonliteral Copyright Infringement, 107 Nw. U. L. Rev. 1821 (2013). Castle Rock Entertainment, Inc. v. Carol Publishing Group, Inc., 150 F.3d 132 (2d Cir. 1998) is the fragmented model: a 643-question trivia book drew every question and correct answer from 84 of the 86 "Seinfeld" episodes then broadcast, and summary judgment went to the copyright owner. Most story and software cases, by contrast, are nonliteral and turn on structure.

What to compare, medium by medium

The table compresses a good deal of case law. For music, the commonplace-elements filter comes from Gray and Structured Asset Sales, LLC v. Sheeran, 120 F.4th 1066 (2d Cir. 2024), which held a four-chord progression and a syncopated harmonic rhythm too commonplace to protect even in combination. For photographs, Ets-Hokin v. Skyy Spirits, Inc., 323 F.3d 763 (9th Cir. 2003) left a product photographer with only a thin copyright once the bottle itself and the conventions of commercial photography were filtered out. For surface designs, Tufenkian Import/Export Ventures, Inc. v. Einstein Moomjy, Inc., 338 F.3d 127 (2d Cir. 2003) protected a rug designer's choices about which public domain motifs to keep and which to drop. For software, Gates Rubber Co. v. Bando Chemical Industries, Ltd., 9 F.3d 823 (10th Cir. 1993) expects filtration findings at each level of abstraction. The most detailed practitioner treatment of comparisons by medium is Robert C. Osterberg & Eric C. Osterberg, Substantial Similarity in Copyright Law (Practising Law Institute).

Two cautions from the software and game cases. First, functional constraints are filtered even when the code was copied literally: in Lexmark International, Inc. v. Static Control Components, Inc., 387 F.3d 522 (6th Cir. 2004), the Sixth Circuit vacated a preliminary injunction because a short printer program whose form was dictated by functional and compatibility constraints was likely unprotectable, and Mitel, Inc. v. Iqtel, Inc., 124 F.3d 1366 (10th Cir. 1997) filtered out telephone command codes dictated by industry practice. Second, game rules are ideas but their artwork is not. In Data East USA, Inc. v. Epyx, Inc., 862 F.2d 204 (9th Cir. 1988), the Ninth Circuit reversed a finding that one karate game infringed another because the shared features (fourteen moves, two-player options, the kicks and punches themselves) flowed from the sport, while in Tetris Holding, LLC v. Xio Interactive, Inc., 863 F. Supp. 2d 394 (D.N.J. 2012), a clone that reproduced the look of the pieces, their bright colors, the ten-by-twenty playfield, and other visual details lost on summary judgment despite its argument that it had copied only rules.

If either work contains AI-generated material, add a column. Material without sufficient human authorship is not protectable, see Thaler v. Perlmutter, 130 F.4th 1039 (D.C. Cir. 2025), and a registration that failed to disclaim it invites a § 411(b) challenge. The registration side is covered in Registering and Protecting Works Made With Generative AI: A Practical Guide.

Assume that anything you hand a testifying expert, and that the expert considers, will be produced. Keep the working chart with counsel and the consulting expert until you are ready to commit to it. A fill-in master similarity and filtration chart, with a companion prior art search log and medium-specific comparison charts, is in the Copyright Infringement Litigation Toolkit: Similarity Charts, Expert Reports, and Filtration Analyses.

Step 3: Choose the court, plead with the works attached, and decide whether to move to dismiss

Where to file

Copyright claims belong in federal court, and venue under § 1400(a) follows the defendant. That still leaves real choices when a defendant can be "found" in several districts, and the choice of circuit changes the test, the role of experts, and the odds of early dismissal; the circuit-by-circuit comparison is in the companion article. A defendant can transfer for convenience under 28 U.S.C. § 1404(a), and an accused party who expects a suit may file first for a declaratory judgment. For a claim worth $30,000 or less, the Copyright Claims Board is a cheaper, voluntary alternative; see The Copyright Claims Board: Small Claims Copyright Litigation Under the CASE Act.

The complaint, for the plaintiff

A complaint in a similarity case must satisfy Bell Atlantic Corp. v. Twombly, 550 U.S. 544 (2007) and Ashcroft v. Iqbal, 556 U.S. 662 (2009) on each element, and it should be written for a judge who will read the works before reading your adjectives.

1. Identify each work and registration, attach the certificates, and plead first-publication and registration dates, which frame § 412.
2. Plead ownership facts: authorship, work for hire, or the signed assignment.
3. Plead access with names and dates. If you rely on wide dissemination, plead numbers (sales, streams, views, chart positions). A handful of social media likes is not dissemination, as Woodland v. Hill, 136 F.4th 1199 (9th Cir. 2025) held.
4. Plead striking similarity in the alternative if the access chain is thin. In Malibu Textiles, Inc. v. Label Lane International, Inc., 922 F.3d 946 (9th Cir. 2019), the Ninth Circuit held that a lace designer plausibly pleaded striking similarity and that denying leave to amend its access allegations was an abuse of discretion; leave to amend is governed by Fed. R. Civ. P. 15(a)(2).
5. Attach or lodge both works. Under Fed. R. Civ. P. 10(c) an exhibit is part of the pleading, and works the complaint relies on are incorporated by reference, Koala v. Khosla, 931 F.3d 887 (9th Cir. 2019). Lodge audio, video, and code on physical or electronic media with the clerk if the court's rules allow.
6. Describe the protectable expression precisely, and plead any selection-and-arrangement theory deliberately. Gaito holds that the works "supersede and control" contrary descriptions, so overstatement backfires.
7. Demand a jury within the time Fed. R. Civ. P. 38(b) allows, and file the notice the clerk sends to the Register of Copyrights under 17 U.S.C. § 508 (Form AO 121 in most districts).

For general pleading craft, see Drafting a Complaint That Survives a Motion to Dismiss.

The motion to dismiss, for the defendant

Courts will compare the works on a Fed. R. Civ. P. 12(b)(6) motion when the works are "capable of examination and comparison," Christianson v. West Publishing Co., 149 F.2d 202 (9th Cir. 1945), and the shared material is plainly unprotectable. The Second Circuit affirmed dismissals in Gaito and in Abdin v. CBS Broadcasting Inc., 971 F.3d 57 (2d Cir. 2020); the Seventh in Peters v. West, 692 F.3d 629 (7th Cir. 2012) and Hobbs v. John, 722 F.3d 1089 (7th Cir. 2013); the Third in Tanksley v. Daniels, 902 F.3d 165 (3d Cir. 2018); and the Ninth in Rentmeester.

The Ninth Circuit has also explained when not to try. In Zindel v. Fox Searchlight Pictures, Inc., No. 18-56087 (9th Cir. June 22, 2020) (unpublished), it reversed the dismissal of a claim that "The Shape of Water" copied Paul Zindel's play "Let Me Hear You Whisper," holding that dismissal requires the works to be before the court, reasonable minds to be unable to differ, and no additional evidence, including expert testimony, that would be material; there, expert literary analysis could illuminate the plausibly alleged shared plot sequence and whether the overlaps were mere tropes. The court relied on 3 William F. Patry, Patry on Copyright § 9:86.50, and 3 Nimmer on Copyright § 12.10[B][3]. In Hanagami v. Epic Games, Inc., 85 F.4th 931 (9th Cir. 2023), it reversed the dismissal of a choreography claim that had been dissected into individually unprotectable poses, and in Hall v. Swift, No. 18-55426 (9th Cir. Oct. 28, 2019) (unpublished), it reversed the dismissal of a lyric claim because originality is normally a question of fact, invoking Justice Holmes's warning in Bleistein v. Donaldson Lithographing Co., 188 U.S. 239 (1903) against judges appointing themselves final arbiters of artistic worth.

How to brief the motion:

1. Lodge both works complete, not excerpts, and cite the plaintiff's own exhibits.
2. Address every similarity the complaint alleges in a filtration table, with the reason each element is unprotectable.
3. Then compare the works as wholes, so the court cannot be accused of the over-dissection Hanagami condemned.
4. Use judicial notice under Fed. R. Evid. 201 sparingly. Genre conventions that anyone can verify are fair game, as in Zella, but third-party prior art offered for its content is a matter outside the pleadings, and Fed. R. Civ. P. 12(d) converts the motion to one for summary judgment if the court considers it.
5. If you have already answered, move for judgment on the pleadings under Rule 12(c). In Shame on You Productions, Inc. v. Banks, 893 F.3d 661 (9th Cir. 2018), the court ordered the parties to exchange the screenplays at the scheduling conference, granted judgment on the pleadings for the makers of "Walk of Shame," and awarded fees the Ninth Circuit affirmed as warranted by an objectively unreasonable claim.

For the plaintiff opposing the motion: show where reasonable minds could differ, say concretely what expert analysis or discovery would add (Zindel), argue originality as a fact question (Hall), and ask for leave to amend. Do not answer with a forty-row list. Dismissals are reviewed de novo, so the court of appeals will compare the works itself. The general Rule 12 standards are in Motions to Dismiss Under Rule 12: A Practical Guide for Plaintiffs and Defendants.

The answer and defenses

Deny copying and plead independent creation, which is technically a denial rather than an affirmative defense but deserves notice. Plead the affirmative defenses that fit: fair use, which the defendant must prove, Campbell v. Acuff-Rose Music, Inc., 510 U.S. 569 (1994), and which turns on the specific use after Andy Warhol Foundation for the Visual Arts, Inc. v. Goldsmith, 598 U.S. 508 (2023); license, which removes licensed elements from the comparison as it did in Apple Computer, Inc. v. Microsoft Corp., 35 F.3d 1435 (9th Cir. 1994); limitations; de minimis use; and invalidity, including originality and § 411(b). Plead merger and scènes à faire as well; many courts treat them as limits on protectability rather than defenses, but pleading them costs nothing. Consider a counterclaim for a declaration of non-infringement, which can keep a merits ruling within reach if the plaintiff tries to walk away once the fee risk becomes clear, although some courts strike counterclaims that merely mirror the complaint. The mechanics are in Answering a Federal Complaint: Denials, Affirmative Defenses, Counterclaims, and Judgment on the Pleadings, and the fair use analysis in Copyright Fair Use: The Four Factors, Transformative Use, and What Warhol Changed.

Step 4: Use the scheduling conference to shape the fight

The parties must confer under Fed. R. Civ. P. 26(f) at least 21 days before the scheduling conference, and the court must issue a scheduling order under Rule 16(b) within 90 days after any defendant is served or 60 days after any defendant appears, whichever is earlier. Rule 16(c)(2) lets the court decide "the appropriateness and timing of summary adjudication," adopt "special procedures" for complex issues or "unusual proof problems," and order early presentation of evidence on a manageable issue. In a similarity case, those powers are worth more than any single discovery request. Six proposals deserve a place in the joint report, and each side should decide which ones help it.

1. Early exchange of the complete works, in every relevant version. The plaintiff in Shame on You refused to produce its own screenplay until the defendants produced all their drafts; the court ordered the exchange, decided the case on the pleadings, and later awarded fees. Do not be that plaintiff.
2. A statement of claimed elements, and a response. Ask the court to order the plaintiff to list the specific elements it claims were copied and the defendant to list each element it contends is unprotectable and why. In SAS Institute, Inc. v. World Programming Ltd., 64 F.4th 1319 (Fed. Cir. 2023), the Federal Circuit approved a pretrial "copyrightability hearing" at which the district court took competing evidence on abstraction and filtration before trial, using the burden-shifting framework of Compulife Software Inc. v. Newman, 959 F.3d 1288 (11th Cir. 2020). Contention interrogatories under Fed. R. Civ. P. 33(a)(2) do the same work more cheaply.
3. Phasing. A defendant with short, comparable works should propose an early summary judgment motion on similarity before damages discovery. A plaintiff who needs access discovery or expert analysis to oppose it should say so now and be ready to invoke Fed. R. Civ. P. 56(d) later.
4. A protective order built for creative files and code. Two tiers (confidential, and highly confidential for attorneys' eyes only), a source code protocol (a standalone review computer, no network, logged printouts), and rules for in-house counsel. In Brown Bag Software v. Symantec Corp., 960 F.2d 1465 (9th Cir. 1992), the Ninth Circuit affirmed an order keeping a plaintiff's in-house counsel, who advised his employer on a "gamut of legal issues, including contracts, marketing, and employment," away from the defendant's trade secrets, and affirmed summary judgment on the copyright claim. See Negotiating a Protective Order and Filing Under Seal: A Practical Guide.
5. An ESI protocol that reaches native creative files. Session files and stems, layered image files, CAD files, and repositories with full commit history, produced with metadata and hash values. PDFs of a layered design file erase the very evidence that dates it.
6. An expert schedule that matches the burdens, with opening reports from the party bearing the burden on each issue, rebuttal reports, and a deadline for challenges to experts aligned with summary judgment.

Add stipulations where you can: which versions are "the works," the authenticity of certified deposits and registration files under Fed. R. Evid. 901, and how audio, video, and code will be lodged. The general planning checklist is Rule 26 Initial Disclosures and Discovery Planning: A Practical Checklist.

If the plaintiff wants a preliminary injunction

A motion under Fed. R. Civ. P. 65 compresses the whole similarity case into weeks. The movant must satisfy Winter v. Natural Resources Defense Council, Inc., 555 U.S. 7 (2008), and irreparable harm "must be proved, not presumed" (the phrase comes from 4 Nimmer on Copyright § 14.06[A][5]) after eBay Inc. v. MercExchange, L.L.C., 547 U.S. 388 (2006), Salinger v. Colting, 607 F.3d 68 (2d Cir. 2010), and Flexible Lifeline Systems, Inc. v. Precision Lift, Inc., 654 F.3d 989 (9th Cir. 2011). Likelihood of success requires a real filtration analysis on an expedited record, and appellate courts reverse injunctions that skip it: Satava v. Lowry, 323 F.3d 805 (9th Cir. 2003) reversed one for a glass jellyfish sculptor whose thin copyright reached only virtually identical copies, and Lexmark vacated another. Injunctions survive when the protectable combination is clear, as in Silvertop Associates Inc. v. Kangaroo Manufacturing Inc., 931 F.3d 215 (3d Cir. 2019), where the combination of a banana costume's non-utilitarian sculptural features was protectable and the defendant conceded substantial similarity. Expect a bond under Rule 65(c), consider consolidating the hearing with trial under Rule 65(a)(2), and remember that an order granting or denying the injunction is immediately appealable under 28 U.S.C. § 1292(a)(1). See Preliminary Injunctions and Temporary Restraining Orders: Emergency Relief in Federal Court.

Step 5: Take the discovery that proves or disproves copying

Similarity discovery is narrow but deep. It tells two stories: how the plaintiff's work could have reached the defendant's creators, and how the defendant's work actually came to be.

The access chain

The plaintiff should trace every path the work traveled. Ask for searches of the defendant's systems for the work's title, the plaintiff's name, and file names; collect submission logs, meeting calendars, nondisclosure agreements, and intake records; take a deposition of the company's designee under Fed. R. Civ. P. 30(b)(6) on how unsolicited submissions are handled; and subpoena agents, labels, publishers, studios, platforms, and conference organizers under Fed. R. Civ. P. 45. The goal is a nexus between the person who received the work and the people who made the accused work. Bare corporate receipt failed in Jorgensen v. Epic/Sony Records, 351 F.3d 46 (2d Cir. 2003); testimony about how an office routinely handled faxes succeeded in Bouchat v. Baltimore Ravens, Inc., 241 F.3d 350 (4th Cir. 2001). Dissemination theories need numbers: in Art Attacks Ink, LLC v. MGA Entertainment Inc., 581 F.3d 1138 (9th Cir. 2009), sales of about 2,000 t-shirts a year, displays at county fairs, and a website did not establish widespread dissemination of a design. And in Design Basics, LLC v. Lexington Homes, Inc., 858 F.3d 1093 (7th Cir. 2017), a plaintiff that had turned home-plan litigation into a revenue stream lost on summary judgment for want of any evidence of access.

The creation record

The defendant should collect and produce its own creation history before the plaintiff asks: dated drafts, sketches, reference boards, session files, commit histories, and the chats around them, with metadata intact and authenticated under Rule 901. That record is the independent creation defense, and it is also where direct evidence of copying hides. Reference boards and mood boards are notorious for containing the plaintiff's work. In Rogers v. Koons, 960 F.2d 301 (2d Cir. 1992), the sculptor had bought a notecard of the photograph, torn off the copyright notice, and sent it to his artisans with instructions to copy it; the Second Circuit affirmed summary judgment for the photographer.

The defendant's discovery runs the other way: the plaintiff's drafts, influences, and reference materials (to find the common source), the plaintiff's earlier works, and any demands the plaintiff has made against other works said to copy the same features. A plaintiff that has accused five unrelated songs of copying one melodic figure is making the defendant's prior art argument for it. A plaintiff, in turn, should ask for the defendant's own copyright applications; a company that claimed protection for a feature in its own registration will find it awkward to call that feature generic.

Written discovery that ends cases

Requests for admission under Fed. R. Civ. P. 36 are deemed admitted if not answered within 30 days. In Jones v. Blige, 558 F.3d 485 (6th Cir. 2009), plaintiffs who failed to respond were held to have admitted that the lyrics were not substantially similar and that two defendants had no access. Calendar every set, and see Strategic Responses to Requests for Admission: A Comprehensive Guide for Legal Practitioners.

Keep the works themselves in the record

The comparison requires the works, in the versions that matter, in admissible form. In Seiler v. Lucasfilm, Ltd., 808 F.2d 1316 (9th Cir. 1987), an artist who claimed "The Empire Strikes Back" copied his creatures could produce only reconstructions; the district court found that he had lost or destroyed the originals in bad faith, so Fed. R. Evid. 1002 and Fed. R. Evid. 1004 barred all secondary evidence, including the copies he had deposited with the Copyright Office, and summary judgment followed. In Antonick v. Electronic Arts, Inc., 841 F.3d 1062 (9th Cir. 2016), a programmer's jury verdict was erased because neither side's source code was ever admitted, leaving the jury nothing to compare. Agree early on the exhibit set of the works, and get certified deposits for anything registered long ago.

Step 6: Retain, disclose, and defend the experts

Match the expert to the step and the circuit

Experts may testify about copying in fact everywhere; Arnstein v. Porter, 154 F.2d 464 (2d Cir. 1946) welcomed "dissection" and expert help on that question. On unlawful appropriation, the rules diverge. The Ninth Circuit admits expert analysis on the objective extrinsic test and excludes it on the subjective intrinsic test, a split that traces to Sid & Marty Krofft Television Productions, Inc. v. McDonald's Corp., 562 F.2d 1157 (9th Cir. 1977) and Shaw v. Lindheim, 919 F.2d 1353 (9th Cir. 1990). The Fourth and Sixth Circuits judge similarity from the perspective of the intended audience; in Kohus v. Mariol, 328 F.3d 848 (6th Cir. 2003), which involved drawings of a playpen latch, the court held that where the audience has specialized expertise relevant to the purchasing decision, the trier of fact adopts that perspective and expert testimony "will usually be necessary." The best account of why the audience matters is Jeanne C. Fromer & Mark A. Lemley, The Audience in Intellectual Property Infringement, 112 Mich. L. Rev. 1251 (2014). Software experts are expected everywhere after Computer Associates International, Inc. v. Altai, Inc., 982 F.2d 693 (2d Cir. 1992), and music experts nearly so after Swirsky v. Carey, 376 F.3d 841 (9th Cir. 2004); for an argument that judges should decide more of the music question themselves, see Joseph P. Fishman, Music as a Matter of Law, 131 Harv. L. Rev. 1861 (2018). Retain a damages expert at the same time, because apportioning profits to the copied expression is often the largest number in the case.

The report

A testifying expert's report must contain everything Fed. R. Civ. P. 26(a)(2)(B) lists: a complete statement of the opinions and their basis, the facts or data considered, exhibits, qualifications and publications from the previous ten years, prior testimony from the previous four years, and compensation. Absent a stipulation or court order, disclosures are due 90 days before trial and rebuttal reports within 30 days of the other side's disclosure. Drafts and most attorney communications are protected under Rule 26(b)(4)(B) and (C), except communications about compensation, facts or data the attorney provided that the expert considered, and assumptions the attorney supplied that the expert relied on.

A report that survives in a similarity case does seven things: identifies the works compared by version and source (the deposit copy, for a 1909 Act work); explains a reproducible method (transcription conventions, key normalization, overlay settings, code comparison parameters); reports a prior art search; filters element by element with reasons; explains the significance of what remains; addresses the differences; and states its limits. The toolkit linked in Step 2 includes an outline for the report and an audit list for attacking the other side's. Opinions disclosed late are excluded under Fed. R. Civ. P. 37(c)(1) unless the failure was substantially justified or harmless; see Rule 37(c)(1) Preclusion of Undisclosed Evidence: A Practical Guide.

The fight over admissibility

Since December 2023, Fed. R. Evid. 702 says expressly that the proponent must show the court it is "more likely than not" that the testimony rests on sufficient facts, reliable methods, and a reliable application of those methods to the case. The court decides that question under Fed. R. Evid. 104(a), applying Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) and Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999) to musicologists and programmers alike. The motions that succeed in similarity cases target:

• The wrong work. Analyzing a famous recording when the registered composition is a 1909 Act deposit copy.
• No filtration, or filtration by assertion. An opinion that lists similarities without explaining which are protectable answers the wrong question.
• Undisclosed manipulation. Transposition, tempo changes, cropping, and rescaling are legitimate only when disclosed and applied to both works.
• No prior art search. The expert in Selle v. Gibb, 741 F.2d 896 (7th Cir. 1984) never addressed coincidence or a common source, and a verdict built on his testimony did not survive.
• Legal conclusions and intrinsic-test opinions. Fed. R. Evid. 704 permits opinions on ultimate issues but not instructions on the law, and in the Ninth Circuit no expert may tell the jury how the works feel.
• Ghost-writing. In Batiste v. Lewis, 976 F.3d 493 (5th Cir. 2020), a jazz musician's "musicologist" admitted at deposition that the plaintiff had performed the analysis himself with software the expert could not check. The report was excluded, the court refused to let the plaintiff refile it in his own name after the deadline because the scheduling order could be changed only for good cause under Fed. R. Civ. P. 16(b)(4), and summary judgment and a fee award against the plaintiff were affirmed.

The stakes can be total. In SAS Institute, the district court excluded the copyright owner's only technical expert, an exclusion the court itself acknowledged left the owner without supportable claims, and the Federal Circuit affirmed over a dissent. Lay opinion about similarity is usually excluded under Fed. R. Evid. 701, though a percipient witness may identify what he heard, as the investigator did in Range Road. Consumer surveys rarely help; Warner Bros. Inc. v. American Broadcasting Cos., 720 F.2d 231 (2d Cir. 1983) refused to let a survey create a jury question about works that were not similar as a matter of law. For deposition strategy, see Taking and Defending an Expert Deposition: A Practical Guide and Expert Witnesses After the 2023 Amendment to Rule 702: Daubert, Disclosure, and Cross-Examination.

Step 7: Win or survive summary judgment

Summary judgment under Fed. R. Civ. P. 56 turns on whether a reasonable jury could find for the nonmovant, Anderson v. Liberty Lobby, Inc., 477 U.S. 242 (1986); Celotex Corp. v. Catrett, 477 U.S. 317 (1986). Unless a local rule or order says otherwise, a party may move any time until 30 days after discovery closes, and Rule 56(f) lets the court grant judgment for a party that did not move, after notice. In similarity cases, judgment is common in both directions.

In the Ninth Circuit, the motion is a fight about the extrinsic test. A plaintiff who fails it loses, as in Kouf v. Walt Disney Pictures & Television, 16 F.3d 1042 (9th Cir. 1994), Funky Films, Inc. v. Time Warner Entertainment Co., 462 F.3d 1072 (9th Cir. 2006), and Benay v. Warner Bros. Entertainment, Inc., 607 F.3d 620 (9th Cir. 2010). A plaintiff who passes it goes to the jury on the intrinsic test (Shaw; L.A. Printex Industries, Inc. v. Aeropostale, Inc., 676 F.3d 841 (9th Cir. 2012)). And a plaintiff can win outright where the works are so close that no reasonable juror could find otherwise, Unicolors, Inc. v. Urban Outfitters, Inc., 853 F.3d 980 (9th Cir. 2017).

In the Second Circuit, the court compares the works itself. It affirmed judgment for builders in Zalewski v. Cicero Builder Dev., Inc., 754 F.3d 95 (2d Cir. 2014), for copyright owners in Castle Rock and Rogers, and reversed in Repp v. Webber, 132 F.3d 882 (2d Cir. 1997) where a district court had weighed competing experts instead of identifying a factual dispute.

In the Eleventh Circuit, judges take the lead on thin works. Intervest Construction, Inc. v. Canterbury Estate Homes, Inc., 554 F.3d 914 (11th Cir. 2008) held that where the question is similarity of protectable expression in a compilation such as a floor plan, it is "often more reliably and accurately resolved in a summary judgment proceeding" because a judge is better able to separate original expression from the rest. In Home Design Services, Inc. v. Turner Heritage Homes Inc., 825 F.3d 1314 (11th Cir. 2016), concurring judges debated whether that approach shortchanges the jury, and Judge Tjoflat defended it as recognizing that thin protection makes more of the analysis legal.

Two techniques matter more than the standard. First, narrow the case even when you cannot end it. Before the Jersey Boys trial in Corbello v. Valli, 974 F.3d 965 (9th Cir. 2020), the district court applied the extrinsic test and let only twelve alleged similarities reach the jury; after a plaintiff's verdict it granted judgment as a matter of law, and the Ninth Circuit affirmed because each of the twelve rested on historical facts, common phrases, scènes à faire, or material the autobiography presented as fact. In Apple v. Microsoft, filtering licensed and unprotectable elements left a comparison that required virtual identity, and Apple chose not to oppose summary judgment on that standard. Second, make the comparison easy. Lodge the works, put the filtration table in the statement of facts with record citations under Rule 56(c)(1), and walk the court through the works in the brief. A nonmovant who needs discovery it has not had must say so by declaration under Rule 56(d), not in a footnote.

Remember the appellate consequences. Summary judgment is reviewed de novo, and in the Second Circuit even a bench finding on a visual comparison is reviewed de novo because, as Boisson v. Banian, Ltd., 273 F.3d 262 (2d Cir. 2001) put it, comparing the products is "a task we may perform as well as the district court." A denial of summary judgment, by contrast, cannot be appealed after a full trial, Ortiz v. Jordan, 562 U.S. 180 (2011); the argument must be renewed at trial under Rule 50. See Summary Judgment Under Rule 56: Winning and Surviving Before Trial.

Step 8: Prepare the trial: instructions, verdict form, and how the jury meets the works

Jury or bench. A jury is the default once demanded, but a bench trial under Fed. R. Civ. P. 52 can suit a defendant with a strong filtration case or a plaintiff with an unsympathetic story. Findings by the judge are no safe harbor: Data East reversed a district court's finding of infringement and its permanent injunction, and Boisson shows the Second Circuit redoing the comparison itself.

Motions in limine. Typical targets are the famous recording in a 1909 Act music case (in Skidmore the district court excluded the "Taurus" recordings even though they were relevant to access, reasoning that the jury might confuse access with similarity, and the en banc court held the point moot because the jury found access anyway); expert opinions on the intrinsic test; lay "they sound the same" opinions; and evidence of wealth, other lawsuits, or unrelated bad acts under Fed. R. Evid. 403.

Instructions. Under Rule 51, a party must request an instruction and then object on the record, promptly, when the court refuses it. In Skidmore, the plaintiff proposed a selection-and-arrangement instruction but never objected when the court omitted it, so review was for plain error only and the claim failed. Instructions must also filter. In Harper House, Inc. v. Thomas Nelson, Inc., 889 F.2d 197 (9th Cir. 1989), a multimillion-dollar verdict for the maker of personal organizers was reversed and a new trial ordered because a "total impact and effect" instruction let the jury find infringement based on unprotectable material rather than the original selection and arrangement. In Bateman v. Mnemonics, Inc., 79 F.3d 1532 (11th Cir. 1996), a software verdict was vacated for a new trial because the court limited filtration to nonliteral similarities, when literally copied code can be unprotectable too. Start from the Ninth Circuit Manual of Model Civil Jury Instructions, chapter 17, or your circuit's pattern instructions (the toolkit linked in Step 2 has draft instructions and a special verdict form), then add case-specific instructions on the deposit copy, the categories of unprotectable material, thin protection and virtual identity where they apply (Apple; Satava; Mattel, Inc. v. MGA Entertainment, Inc., 616 F.3d 904 (9th Cir. 2010)), access as a reasonable possibility (Three Boys Music Corp. v. Bolton, 212 F.3d 477 (9th Cir. 2000)), striking similarity, independent creation, and subconscious copying.

The verdict form. Use special questions under Fed. R. Civ. P. 49. The Skidmore jury answered in sequence that the plaintiff owned the copyright, that Led Zeppelin had access, and that the songs were not substantially similar under the extrinsic test, which made the verdict easy to defend on appeal. A plaintiff with several works or theories wants a separate question for each.

How the jury meets the works. The court controls the mode of presentation under Fed. R. Evid. 611(a). Agree on neutral renditions of deposit copies (in Williams v. Gaye, the defense musicologist played her own recording of the deposit copy of "Got To Give It Up"), synchronized side-by-side video, and code excerpts with line numbers. Summaries are admissible under Fed. R. Evid. 1006, and illustrative aids are now governed by Federal Rule of Evidence 107, added in December 2024. Exchange demonstratives early and test every transposition, overlay, and highlight. Consider separating liability from damages under Fed. R. Civ. P. 42(b), especially where profits evidence would color the similarity question. For trial mechanics, see Jury Trial Toolkit: Voir Dire, Openings, Exhibits, and Instructions and Trial Exhibits and Demonstratives: Getting Evidence in Front of the Jury and Keeping It There.

Step 9: Try the case, preserve the record, and handle post-trial motions and appeal

At trial, the plaintiff tells a creation story, an access story, and a copying story, and then shows the protectable heart of the work. The defendant answers with its own dated creation record, the prior art, and the differences. Everything else is preservation.

1. Move under Rule 50(a) before the case goes to the jury, specifying the judgment sought and the law and facts that support it. In Williams v. Gaye, neither side did, so neither the district court nor the Ninth Circuit could enter judgment as a matter of law after the verdict, and the dissent's view that the songs were not similar as a matter of law could not be acted on.
2. Object to inconsistent verdicts before the jury is discharged. The Gaye court held one side's inconsistency argument waived for failure to do so.
3. Renew under Rule 50(b) within 28 days after judgment, joined with any Rule 59 request for a new trial. Failing to renew forfeits appellate review of the sufficiency of the evidence, Unitherm Food Systems, Inc. v. Swift-Eckrich, Inc., 546 U.S. 394 (2006). The deadline is not jurisdictional, so an opponent can forfeit a timeliness objection, as happened in Art Attacks, but no one should plan around that.
4. Expect post-verdict scrutiny of similarity. Verdicts for plaintiffs in similarity cases are set aside more often than most: Selle (judgment notwithstanding the verdict for the Bee Gees), Gray (judgment as a matter of law after a $2.8 million verdict), Corbello, and Antonick all ended that way. Motions for a new trial under Fed. R. Civ. P. 59 are reviewed deferentially, which is why the Gaye verdict survived.
5. Calendar the appeal. A notice of appeal is due 30 days after entry of judgment under Fed. R. App. P. 4(a)(1)(A), and a timely Rule 50(b), 52(b), or 59 motion resets the clock under Rule 4(a)(4); a fee motion does not unless the court orders otherwise under Fed. R. Civ. P. 58(e). Appeals lie from final judgments under 28 U.S.C. § 1291, and interlocutory review of a controlling question requires certification under § 1292(b).

The mechanics are covered in Filing or Opposing Post-Trial Motions Under Rules 50, 59, and 60: A Practical Guide and Federal Appellate Practice: Preserving Error, Standards of Review, and Briefs That Win.

Step 10: Fees, costs, settlement, and what each stage costs

Fees. Under § 505 the court may award a reasonable fee to the prevailing party, plaintiff or defendant, on the same terms, Fogerty v. Fantasy, Inc., 510 U.S. 517 (1994), giving substantial weight to the objective reasonableness of the losing position, Kirtsaeng v. John Wiley & Sons, Inc., 579 U.S. 197 (2016). Defendants who beat weak similarity claims collect: Shame on You and Batiste both affirmed defense awards. Plaintiffs whose registrations came too late cannot recover fees at all under § 412. The motion is due 14 days after judgment under Fed. R. Civ. P. 54(d)(2). "Full costs" means only the categories in 28 U.S.C. § 1920, Rimini Street, Inc. v. Oracle USA, Inc., 586 U.S. 334 (2019), so expert fees are usually unrecoverable. An offer of judgment under Fed. R. Civ. P. 68 can shift post-offer costs, and in some circuits fees: compare Jordan v. Time, Inc., 111 F.3d 102 (11th Cir. 1997) with Harbor Motor Co. v. Arnell Chevrolet-Geo, Inc., 265 F.3d 638 (7th Cir. 2001).

Remedies that frame settlement. Actual damages and the infringer's profits under 17 U.S.C. § 504(b) (the plaintiff proves gross revenue; the defendant proves deductions and the share of profit attributable to other factors, the apportionment approved in Sheldon v. Metro-Goldwyn Pictures Corp., 309 U.S. 390 (1940)); statutory damages under § 504(c) for timely registered works; discretionary injunctions under 17 U.S.C. § 502; and impoundment under 17 U.S.C. § 503. See Copyright Damages and Remedies: Statutory Damages, Profits, Injunctions, and Fees.

Settlement windows. Leverage shifts at predictable points: after the demand letter, after the ruling on a motion to dismiss, after the claimed-elements exchange, after expert reports, after summary judgment, and on the eve of trial. Music cases tend to settle for a writing credit and a share of publishing income; software and design cases for a license, a redesign, or a withdrawal from the market; literary and film cases, which plaintiffs lose often, for a walk-away after a dispositive motion. Keep negotiations within Rule 408, and see Mediation and Settlement: Preparing, Negotiating, and Documenting the Deal.

What each stage costs. The ranges below are rough estimates from our experience for one side in a contested federal case; they vary with the market, the medium, and the number of works and experts.

A case that ends on a motion to dismiss usually costs each side in the high five figures to low six figures; one litigated through summary judgment commonly costs several hundred thousand dollars and can pass a million. For recovering what you can, see the Fee Shifting and Litigation Cost Recovery Toolkit.

Common mistakes, and the cases that show the price

• Suing too early or on the wrong work. Filing on a pending application (Fourth Estate), or registering one version and proving another (Airframe).
• Pleading with adjectives and lists. The works control over descriptions (Gaito), and random lists are "inherently subjective and unreliable" (Litchfield).
• Moving to dismiss when the court will want experts, or failing to move when the works speak for themselves (Zindel versus Abdin).
• Ignoring requests for admission (Jones v. Blige).
• Losing the originals or never admitting the works (Seiler; Antonick).
• Letting the client write the expert report (Batiste), or relying on a single expert whose exclusion ends the case (SAS Institute).
• Comparing the recording when the law compares the deposit copy (Skidmore; Williams v. Gaye).
• Instructions that do not filter (Harper House; Bateman), or requesting an instruction without objecting when it is refused (Skidmore).
• Skipping the Rule 50(a) motion (Williams v. Gaye) or the Rule 50(b) renewal (Unitherm).
• Ignoring fee exposure, which threatens plaintiffs as well as defendants (Shame on You; Batiste), and forgetting that § 412 can take fees off the table for the plaintiff alone.

A worked example: the puzzle game clone, from first look to mediation

Tidewater Puzzle Co., a three-person studio in Portland, makes "Saltmarsh," a tile-matching game whose pieces are hand-painted tide-pool creatures on a hexagonal board, with a "bloom" animation when a match clears. Tidewater registered version 1.0 within two months of release. Version 1.2, released publicly five months later, redrew the crab and octopus tiles and added the bloom. A week after that release, Tidewater pitched the game at an industry showcase and, under a nondisclosure agreement, sent a 1.2 build to the business development director of Halvorsen Interactive, a Seattle publisher. Halvorsen passed. Fourteen months later it released "Reef Rush."

Month 0: assessment. Counsel's first-pass chart has 31 rows. Nineteen are mechanics (the hexagonal board, three-in-a-row matching, a "tide" that pushes pieces toward shore each turn), which are ideas under the reasoning of Data East and Tetris. Twelve are expression: six creature tiles that track Saltmarsh's line work nearly stroke for stroke, three rows on the bloom animation (its timing, petal shapes, and color sequence), the palette, and two rows on the layout of the score panel. Counsel files an application for version 1.2 as a derivative work with special handling, and the certificate issues in nine days. The § 412 math is now clear: the material from version 1.0 supports statutory damages and fees, but the tiles redrawn in 1.2 and the bloom, registered only after Reef Rush launched, support only actual damages and profits. (For game registration practice, see Copyright Registration of Games.)

Months 2 to 4: demand and complaint. Both companies sit in the Ninth Circuit, so a declaratory judgment race carries little forum risk, and Tidewater sends a demand with a preservation request. Halvorsen denies copying and cites genre conventions. Tidewater sues in the Western District of Washington, attaching gameplay captures, side-by-side tiles, both registrations, and a breach of contract count for the nondisclosure agreement. It pleads the access chain with names and dates: the build went to the business development director, who reports to the head of the studio that made Reef Rush, and Halvorsen's public development blog dates the start of Reef Rush to six weeks after the showcase.

Month 7: motion to dismiss. Halvorsen argues that everything is mechanics. The court agrees as to the board, the matching, and the tide, and dismisses the claim to that extent, but denies the motion as to the tiles, the bloom, the palette, and the layout, citing Zindel for the point that expert analysis may help evaluate the animation.

Month 9: scheduling order. On the parties' joint proposal, the court orders an exchange of every build within 21 days, Tidewater's statement of claimed elements within 45 days, Halvorsen's unprotectability contentions 30 days later, a source code protocol, production of native art files with layer and commit history, and summary judgment on liability at month 20.

Months 10 to 16: discovery. Halvorsen's art repository holds a layered file for the first Reef Rush crab tile with a hidden layer containing a Saltmarsh screenshot, deleted in a later commit that version control preserved. A chat message from the art lead says to "match the Saltmarsh vibe but make it legally different." Halvorsen's discovery lands a blow too: Saltmarsh's jellyfish tile closely follows a 1904 scientific illustration in the public domain, and Tidewater's founder admits using it as a reference. Tidewater withdraws the jellyfish tile, leaving five.

Months 15 to 18: experts. Tidewater's game artist and forensic examiner present overlays and layer metadata; Halvorsen's game historian compiles forty earlier ocean-themed matching games. The court excludes the paragraph of Tidewater's artist report opining on "total concept and feel," which is for the jury under the intrinsic test, and admits the rest.

Months 20 to 22: summary judgment. The court grants Halvorsen judgment on the palette and score panel, which are commonplace in the genre and at most thinly protected, denies both sides on the five tiles and the bloom, and rules on Tidewater's cross-motion that no reasonable jury could find the crab tile independently created, leaving unlawful appropriation for trial.

Month 23: mediation. Halvorsen faces a jury with the hidden layer and the chat message, a claim to a share of the profits on roughly $14 million in Reef Rush revenue (Tidewater's damages expert attributes 6 to 9 percent of the game's success to the copied art; Halvorsen's says under 2 percent), and fee exposure on the claims built on version 1.0. Tidewater faces the § 412 limits on its strongest tiles, a narrowed case, and about $650,000 in its own fees. They settle: Halvorsen replaces the five tiles and the bloom in an update within 60 days and pays $1.1 million, with mutual releases, no admission, each side bearing its own fees, and a dismissal with prejudice.

What each side should take from it. Tidewater won its leverage in two places, registering the version that was actually sent and demanding native files, and it protected its credibility by filtering its own public domain source before Halvorsen could make it the centerpiece of a motion. Halvorsen won the mechanics fight early and narrowed the case at summary judgment, but its art process, not its lawyers, decided the outcome. A reference layer that should never have existed, and a message no one should have sent, did more damage than any expert.

Frequently asked questions

Does a judge or a jury decide substantial similarity? Both, at different stages. Judges decide protectability, apply the extrinsic test in the Ninth Circuit, and end cases whenever no reasonable jury could find for one side; juries decide genuine disputes and, in the Ninth Circuit, the intrinsic test.

Do I need an expert? For music and software, practically yes. For stories and images, often not at the pleading stage, though Zindel shows that a court may want expert literary analysis before deciding. On copying in fact, an expert who can rule out coincidence and common sources is valuable in every medium.

Can I sue while my application is pending? No. Under Fourth Estate you must wait for the Copyright Office to register or refuse the claim; § 411(a) lets you sue after a refusal if you serve notice on the Register. Special handling shortens the wait to days.

What if I registered a different version from the one that was copied? Register the version that was copied now, claiming the new material. The earlier registration still covers the earlier material, but § 412 may limit remedies for the new material, and you must be able to prove the content of whatever version you sue on.

How long does a case take, and what does it cost? A case that does not settle typically runs eighteen months to three years to verdict. See the cost table in Step 10; dismissal-stage cases cost far less than cases that reach expert discovery.

Should a defendant always move to dismiss? No. Move when the works are short, fully before the court, and the overlap is plainly unprotectable. Otherwise build the record for summary judgment, where filtration and prior art can be proved rather than argued.

Can the loser be ordered to pay the winner's fees? Yes, either side, in the court's discretion under § 505, with heavy weight on whether the losing position was objectively reasonable. A plaintiff whose registration came too late under § 412 cannot recover fees but can still be ordered to pay them.

Is the Copyright Claims Board an alternative? For claims of $30,000 or less, yes, but the respondent can opt out, and complex similarity disputes with experts fit poorly. See the Board guide linked above.

Practical takeaways

• Build the comparison chart, with filtration and prior art columns, before you file or answer, and revise it at every stage.
• Register the version that was copied, get the deposit, and run the § 412 numbers before demanding anything.
• Attach or lodge the complete works; let the judge see them early.
• Use the Rule 16 conference to force an exchange of works, claimed elements, and contentions, and to set a realistic expert schedule.
• Preserve and produce native creative files with their history; that is where copying is proved and independent creation is shown.
• Retain experts early, keep them independent, and make every method reproducible under Rule 702.
• Narrow the case at summary judgment even when you cannot end it.
• Request and object to instructions, use special verdict questions, and make the Rule 50(a) motion before the jury retires.
• Treat fee exposure under § 505 as a live variable from the first letter to the last motion.

This document is general information, not legal advice for any particular situation; the law changes, and the facts matter.

Related Documents

Related Articles

• Proving Copyright Infringement: Access, Substantial Similarity, and the Tests Courts Actually Use: the doctrine behind every step of this guide, circuit by circuit.
• The Copyright Claims Board: Small Claims Copyright Litigation Under the CASE Act: the voluntary small-claims alternative and when it fits.
• Expert Depositions: Taking Apart the Opinion, Protecting Your Own Expert, and Building the Daubert Record: how expert testimony is tested before trial.
• Post-Trial Motions in Federal Court: Judgment as a Matter of Law, New Trial, Remittitur, and Relief From Judgment: the standards behind the verdicts that were set aside.
• Using Depositions at Trial and on Summary Judgment: Rule 32, Designations, Errata Sheets, and Impeachment: putting creator and expert testimony into the record.
• Copyright Damages and Remedies: Statutory Damages, Profits, Injunctions, and Fees: what a win is worth and how apportionment works.
• Copyright Registration: A Comprehensive Guide: registration, deposits, special handling, and supplementary registration.
• Legal Protection of Software: Copyrights, Patents, Trade Secrets, and Contracts: the wider toolkit when code is copied.

Related Guides

• Bringing or Defending a Claim Before the Copyright Claims Board: A Practical Guide: step-by-step Board procedure for both sides.
• Registering and Protecting Works Made With Generative AI: A Practical Guide: disclaimers and records when AI material is in the work.
• Taking and Defending an Expert Deposition: A Practical Guide: outlines and defense strategy for musicologists, programmers, and damages experts.
• Filing or Opposing Post-Trial Motions Under Rules 50, 59, and 60: A Practical Guide: deadlines and drafting for the motions in Step 9.
• Motions to Dismiss Under Rule 12: A Practical Guide for Plaintiffs and Defendants: the general standards behind Step 3.
• Responding to a Cease and Desist Letter: A Practical Guide: the accused party's first moves.
• Negotiating a Protective Order and Filing Under Seal: A Practical Guide: source code and attorneys'-eyes-only provisions.
• Conducting a Fair Use Analysis: A Practical Guide: the defense that often travels with a similarity case.

Related Checklists

• Copyright Infringement Claim Evaluation Checklist: A Practical Checklist: a fast screen of ownership, registration, access, and similarity.
• Expert Disclosure and Daubert Challenge Checklist: A Practical Checklist: Rule 26 disclosures and Rule 702 motions, item by item.
• Rule 26 Initial Disclosures and Discovery Planning: A Practical Checklist: the Rule 26(f) report and scheduling proposals.

Related Toolkits

• Copyright Infringement Litigation Toolkit: Similarity Charts, Expert Reports, and Filtration Analyses: fill-in charts, report outlines, and filtration memos for this guide.
• Jury Trial Toolkit: Voir Dire, Openings, Exhibits, and Instructions: trial materials, including instruction and verdict form templates.
• Fee Shifting and Litigation Cost Recovery Toolkit: preparing and opposing fee and cost applications.