Obviousness is the highest, most frequently encountered, and most slippery hurdle between an inventor and an enforceable patent. Unlike anticipation, § 103 asks a counterfactual, judgment-laden question—would the claimed invention as a whole have been obvious to a person of ordinary skill in the art (POSITA) before the effective filing date?—and lets the examiner combine references, modify a single reference, or invoke "common sense." Because the inquiry is so open-textured, most prosecution responses are won and lost here. This checklist gives you the moves. For the doctrine in full, pair it with overcoming obviousness rejections: a comprehensive guide to Section 103 analysis and the procedural responding to a patent office action checklist.

Phase 1 — Set the frame

  • Confirm which regime applies (post-AIA § 103 for effective filing dates on/after March 16, 2013; pre-AIA otherwise)—it changes what qualifies as prior art.
  • Verify the examiner's claim construction under broadest reasonable interpretation; anchor terms in your specification (Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005)).
  • Pin down the level of ordinary skill (the POSITA). A higher skill level makes combinations look more obvious; argue for the modest, defensible level the field actually supports (Daiichi Sankyo Co. v. Apotex, Inc., 501 F.3d 1254 (Fed. Cir. 2007)).
  • Identify the primary reference, the secondary references, and exactly which limitation each is cited to supply.

Phase 2 — Test the prima facie case (the cheapest win)

  • Confirm the examiner identified all the differences between the claim and the prior art, with a faithful mapping of every limitation.
  • Confirm the examiner articulated a reason a POSITA would have combined or modified the references (the motivation requirement—the heart of the case).
  • Confirm the examiner established a reasonable expectation of success (MPEP § 2143.02; In re Kubin, 561 F.3d 1351 (Fed. Cir. 2009)).
  • If any element is missing, say so directly—the most efficient win costs nothing in claim scope.

Why this matters. The examiner bears the initial burden of a prima facie case (MPEP §§ 2142, 2143); only then does the burden shift to you. Showing the case was never properly made is the first and best line of attack.

Phase 3 — Check the cited KSR rationale against its predicates

  • Identify which MPEP § 2143 rationale the examiner invoked (e.g., combine known elements for predictable results; simple substitution; obvious to try; design incentive/market force; surviving TSM).
  • Hold the rationale to its factual predicates—the rationale is a label, not a conclusion.
  • For "obvious to try," confirm there genuinely was a finite number of identified, predictable solutions, not "throwing darts at a board" (In re Kubin, 561 F.3d at 1359).
  • For "simple substitution," confirm the substituted element was a known equivalent functioning the same way for a predictable result.
  • Quote the MPEP's own requirements back to the examiner—reframe the dispute from "is this obvious?" to "has the examiner met the agency's checklist?"

Phase 4 — Attack the motivation to combine

  • Argue the references are too different to combine (disparate fields, scales, or purposes weigh against motivation—Adidas AG v. Nike, Inc., 963 F.3d 1355 (Fed. Cir. 2020)).
  • Expose conclusory combinations—"obvious because it yields predictable results," with no explanation of why predictable or what prompts the combination (In re NuVasive, Inc., 842 F.3d 1376 (Fed. Cir. 2016); Arendi S.A.R.L. v. Apple Inc., 832 F.3d 1355 (Fed. Cir. 2016)).
  • Show the combination would defeat a reference's purpose or render it inoperable (In re Gordon, 733 F.2d 900 (Fed. Cir. 1984)).
  • Name impermissible hindsight: the only "reason" is the applicant's own disclosure used as a roadmap.

Phase 5 — Negate the reasonable expectation of success

  • Distinguish motivation from expectation—one can want to combine and still lack any basis to expect success (Intelligent Bio-Systems, Inc. v. Illumina Cambridge Ltd., 821 F.3d 1359 (Fed. Cir. 2016)).
  • Frame the predictability of the art: in unpredictable arts (chemistry, pharma, biotech), the prima facie case demands a specific motivation and concrete evidence (often data) of expected success (In re Kubin; Eisai Co. v. Dr. Reddy's Laboratories, Ltd., 533 F.3d 1353 (Fed. Cir. 2008)).
  • Show the art gave no indication which parameters were critical or which option would succeed.

Phase 6 — Deploy the other primary-factor rebuttals

  • Teaching away: a reference that criticizes, discredits, or warns against the examiner's path (In re Gurley, 27 F.3d 551 (Fed. Cir. 1994)).
  • Change in principle of operation / unsatisfactory for intended purpose (In re Ratti, 270 F.2d 810 (C.C.P.A. 1959)).
  • Non-analogous art: the reference is neither from the inventor's field nor reasonably pertinent to the problem.
  • Build the affirmative Graham record: scope/content of the art, the precise missing element/arrangement, what a POSITA actually knew, and the objective evidence.

Phase 7 — Marshal objective indicia (secondary considerations)

  • Gather evidence in the recognized categories: commercial success, long-felt but unmet need, failure of others, unexpected results, skepticism of experts, copying by competitors, industry praise, and licensing.
  • Establish nexus—tie the evidence to the claimed features, not to a brand, price, or unclaimed feature (Demaco Corp. v. F. Von Langsdorff Licensing Ltd., 851 F.2d 1387 (Fed. Cir. 1988)).
  • Present indicia via declaration (executive for sales/market share; technologist for unexpected results; industry figure for skepticism).
  • Insist the indicia be weighed as part of the obviousness determination, not as an after-the-fact tiebreaker (In re Cyclobenzaprine Hydrochloride, 676 F.3d 1063 (Fed. Cir. 2012); Apple Inc. v. Samsung Electronics Co., 839 F.3d 1034 (Fed. Cir. 2016) (en banc)).

Phase 8 — Decide on amendment vs. argument

  • Argue first where you can—a clean argument keeps full scope at no estoppel cost.
  • If you amend, add a limitation the combined art genuinely does not teach, supported by the original specification, that still reads on your commercial embodiment.
  • Remember every narrowing amendment triggers prosecution-history estoppel (Festo, 535 U.S. 722 (2002)); keep dependent-claim fallbacks.

Phase 9 — Build the evidentiary record and use the interview

  • Draft Rule 1.132 declarations that are specific, supported (reasoned, not asserted), and credible; include the 18 U.S.C. § 1001 acknowledgment if styled as a declaration.
  • Request an examiner interview to test a proposed amendment and dispel misunderstandings before committing them to the record.
  • Observe the duty of candor: disclose material prior art known to you; do not overstate what a reference lacks.

Phase 10 — Know the forum and its burden

  • In prosecution, the examiner must make the prima facie case before the burden shifts to you.
  • At the PTAB, factual findings are reviewed for substantial evidence; the legal conclusion of obviousness de novo.
  • In district court, an issued patent is presumed valid and a challenger must prove obviousness by clear and convincing evidence.

Common mistakes

  • Conceding the prima facie case instead of testing whether it was ever properly made.
  • Treating a KSR rationale as self-proving—every rationale has predicates.
  • Offering secondary-considerations evidence with no nexus to the claims.
  • Reflexive amendment that whittles claims into commercially worthless scope.
  • Conflating motivation with reasonable expectation of success.

Primary authority

  • 35 U.S.C. § 103. MPEP §§ 2141–2145 (obviousness), 2143 (rationales), 2143.02 (reasonable expectation of success).
  • Graham v. John Deere Co., 383 U.S. 1 (1966); KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007); In re NuVasive, Inc., 842 F.3d 1376 (Fed. Cir. 2016); Arendi S.A.R.L. v. Apple Inc., 832 F.3d 1355 (Fed. Cir. 2016); In re Kubin, 561 F.3d 1351 (Fed. Cir. 2009); In re Gurley, 27 F.3d 551 (Fed. Cir. 1994); In re Gordon, 733 F.2d 900 (Fed. Cir. 1984); Demaco Corp. v. F. Von Langsdorff Licensing Ltd., 851 F.2d 1387 (Fed. Cir. 1988); Apple Inc. v. Samsung Electronics Co., 839 F.3d 1034 (Fed. Cir. 2016) (en banc).

This checklist is general information, not legal advice. Consult a registered patent practitioner.

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