A company can spend years and tens of millions developing an invention, emerge with a granted patent that looks bulletproof, and then watch a single overlooked email or undisclosed reference render the entire patent—often along with related patents in the same family—unenforceable. That is inequitable conduct, the Federal Circuit's "atomic bomb" of patent law. The best defense is a disciplined compliance program that makes candor the default. This checklist provides one. For the doctrine in depth, pair it with inequitable conduct in patent prosecution: navigating the atomic bomb of patent law and the evidence-side companion finding evidence of inequitable conduct in patent prosecution.

Phase 1 — Know the standard you are guarding against

  • Understand the duty of candor under 37 C.F.R. § 1.56: everyone substantively involved must disclose information material to patentability that they know of.
  • Understand the Therasense test: a challenger must prove but-for materiality and specific intent to deceive, each by clear and convincing evidence, with deceptive intent being the single most reasonable inference (Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011) (en banc)).
  • Note materiality and intent are independent—the sliding scale is dead; a strong materiality record buys nothing on intent.
  • Note the narrow egregious-misconduct exception: an unmistakably false affidavit or declaration is material per se (mere nondisclosure of a reference never qualifies).
  • Recall infectious unenforceability: misconduct in one patent can spread to related patents bearing an "immediate and necessary relation" (Consolidated Aluminum Corp. v. Foseco International Ltd., 910 F.2d 804 (Fed. Cir. 1990)).

Phase 2 — Identify who owes the duty

  • Each named inventor (who also acknowledges the duty in the inventor's oath/declaration under 37 C.F.R. § 1.63(c)).
  • Each attorney or patent agent preparing or prosecuting the application.
  • Every other substantively involved person—in-house counsel, scientific staff, regulatory personnel, licensing managers, and officers.
  • Confirm everyone understands the duty runs throughout pendency, up to grant, and that disclosing to the prosecuting attorney discharges an individual's duty.

Phase 3 — Educate everyone who touches the application

  • Give each inventor and relevant employee a plain-language explanation: what must be disclosed, who is covered, that the duty continues to grant, and that violation can cost the entire patent (and family).
  • Present the § 1.63(c) candor acknowledgment as a real obligation, not boilerplate.
  • Repeat a short candor reminder in every substantive client communication during prosecution.

Phase 4 — Gather and cross-route material information

  • Instruct inventors to surface all potentially relevant information: prior products, publications, public uses, offers for sale, testing (including failed experiments), competitor activity, and related litigation or regulatory filings.
  • Identify the material categories: prior art (§ 102), double-patenting references, enablement/written-description data, inventorship/ownership facts, related-application and foreign-counterpart office actions and search reports, conflicting other-agency (e.g., FDA) submissions, and inconsistent statements.
  • Maintain a centralized docket that routes material information identified in any one matter to every related matter automatically—the single best defense against both ordinary lapses and infectious unenforceability.
  • Use the USPTO's Global Dossier to pull foreign family office actions and cited references into the U.S. record.
  • Do not make conclusions about materiality at the inventor level—list what is known and let counsel decide; remember disclosing a reference is not an admission of materiality (37 C.F.R. § 1.97(h)).

Phase 5 — Draft candor-compliant applications and declarations

  • Do not mischaracterize the prior art.
  • Keep prophetic examples in present or future tense; never present a predicted experiment as a completed one (the tense of one verb has decided cases—Purdue Pharma L.P. v. Endo Pharmaceuticals Inc., 438 F.3d 1123 (Fed. Cir. 2006)).
  • Do not cherry-pick favorable data while suppressing unfavorable results.
  • Scrutinize every declaration/affidavit—each factual assertion must be literally true and must not create a false impression by omission (Intellect Wireless, Inc. v. HTC Corp., 732 F.3d 1339 (Fed. Cir. 2013)).
  • Reconcile statements across agencies—do not tell the USPTO a range is "critical" while telling the FDA it is old and well known (Belcher Pharmaceuticals, LLC v. Hospira, Inc., 11 F.4th 1345 (Fed. Cir. 2021)).
  • Get inventorship right (a deceptive naming/omission can be inequitable conduct; innocent errors are correctable under 35 U.S.C. § 256). See preparing an invention disclosure checklist.

Phase 6 — File timely, complete IDSs (37 C.F.R. §§ 1.97–1.98)

  • File an IDS in the early window (within 3 months of filing or before the first office action) for no fee and no certification—the cleanest path.
  • After the first office action, file with the required fee or § 1.97(e) certification.
  • After final rejection or notice of allowance, file with fee and § 1.97(d)–(e) certification—and if counsel cannot truthfully certify, do not file; use an RCE with the IDS attached.
  • After issue-fee payment, use QPIDS, withdrawal-from-issue plus RCE, a continuing application, or supplemental examination.
  • Meet § 1.98 content rules: list each item, provide copies of non-U.S.-patent references, and supply a concise relevance explanation and any English translation for foreign-language references.
  • Verify the examiner initialed each reference as "considered"—an uninitialed reference was not formally placed before the Office (MPEP § 609.05).
  • File supplemental IDSs promptly whenever new material information surfaces (after an office action, after a foreign counterpart is examined, or after litigation produces new art).

Phase 7 — Avoid the IDS traps

  • Do not bury critical references in a haystack of marginal ones; disclose generously but flag the genuinely critical references.
  • For a foreign-language reference, submit the reference, submit the translation you have, and expressly flag its limitations—never translate only the favorable passages (Semiconductor Energy Laboratory Co. v. Samsung Electronics Co., 204 F.3d 1368 (Fed. Cir. 2000)).
  • Do not let patent-term-adjustment optimization tempt you into delaying or omitting a disclosure—a few days of term are never worth an unenforceability risk.

Phase 8 — Correct errors expressly

  • If any misstatement or misleading impression is found—in the specification, an argument, or a declaration—make an express correction that identifies both the error and the corrected information; a quiet, ambiguous walk-back does not cure it (Intellect Wireless; MPEP § 2011).

Phase 9 — Cure post-grant problems with supplemental examination

  • Where a candor gap is discovered in a valuable, in-force patent, evaluate supplemental examination under 35 U.S.C. § 257—it can reach any patentability question (not just patents/printed publications) and can immunize the patent against an inequitable-conduct charge on the information considered (§ 257(c)(1)).
  • Act before any inequitable-conduct allegation is pleaded—the protection is forfeited once you are in the crosshairs (§ 257(c)(2)); any resulting reexamination must conclude before the action is brought.
  • Compare with reissue (§ 251) and patent-owner ex parte reexamination, neither of which carries § 257's immunity.
  • Note the USPTO may refer material fraud to the Attorney General (§ 257(e))—supplemental examination is not a shield against criminal fraud or Walker Process antitrust exposure.

Phase 10 — Defend in litigation

  • Hold a pleaded inequitable-conduct claim to Rule 9(b) particularity—the who, what, when, where, and how, with facts supporting a reasonable inference of knowledge and specific intent (Exergen Corp. v. Wal-Mart Stores, Inc., 575 F.3d 1312 (Fed. Cir. 2009)). A well-aimed motion to dismiss removes the cloud early.
  • Preserve a clean prosecution record and contemporaneous documentation of good-faith judgment calls.
  • Manage privilege deliberately—asserting good-faith reliance can waive privilege over prosecution communications.
  • Remember candor and clean-hands obligations extend into enforcement; litigation misconduct can support an adverse inference of prosecution-era intent (Regeneron Pharmaceuticals, Inc. v. Merus N.V., 864 F.3d 1343 (Fed. Cir. 2017)).

Common mistakes

  • Treating candor as application-by-application instead of a portfolio-wide discipline (infectious unenforceability).
  • Hiding a failed experiment—precisely the data a court will use against you.
  • A false or half-true declaration—the egregious-misconduct exception bites hardest here.
  • Withholding a related-application rejection or a conflicting FDA submission.
  • Curing a misstatement quietly—the correction must be unmistakable.
  • Racing to supplemental examination only after suit—too late.

Primary authority

  • 37 C.F.R. §§ 1.56, 1.63(c), 1.97, 1.98, 1.555, 11.303. 35 U.S.C. §§ 251, 256, 257. Fed. R. Civ. P. 9(b).
  • Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011) (en banc); Kingsdown Medical Consultants, Ltd. v. Hollister Inc., 863 F.2d 867 (Fed. Cir. 1988) (en banc); Intellect Wireless, Inc. v. HTC Corp., 732 F.3d 1339 (Fed. Cir. 2013); Belcher Pharmaceuticals, LLC v. Hospira, Inc., 11 F.4th 1345 (Fed. Cir. 2021); Regeneron Pharmaceuticals, Inc. v. Merus N.V., 864 F.3d 1343 (Fed. Cir. 2017); Consolidated Aluminum Corp. v. Foseco International Ltd., 910 F.2d 804 (Fed. Cir. 1990); Exergen Corp. v. Wal-Mart Stores, Inc., 575 F.3d 1312 (Fed. Cir. 2009); Semiconductor Energy Laboratory Co. v. Samsung Electronics Co., 204 F.3d 1368 (Fed. Cir. 2000).
  • USPTO MPEP §§ 2000.01, 2001.04, 2001.06, 2011, 609.04–609.05; Global Dossier (https://www.uspto.gov/patents/search/global-dossier-initiative).

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

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