Patent Misuse

Patent misuse is an equitable affirmative defense available to patent infringement defendants, which renders a patent unenforceable when the patent holder has used the patent in an improper way that extends its scope or term beyond its lawful limits. The doctrine arises from the equitable maxim that a party coming to court seeking relief (like an injunction) must come with 'clean hands' — if a patent holder has behaved improperly with respect to the patent, courts will not enforce it. Key characteristics: (1) Patent misuse makes the patent UNENFORCEABLE (not invalid) — the patent itself is not canceled, but the court will refuse to enforce it against defendants while the misuse exists. After the misuse is 'purged,' the patent can be enforced going forward. (2) Any defendant can raise misuse — unlike antitrust law, there is no requirement that the defendant itself was harmed by the misuse. Even a defendant who had no contact with the offending licensing arrangement can raise misuse. (3) The historical core of misuse is extending the patent beyond its lawful scope — using patent rights to control things the patent does not cover. Examples: requiring licensees to pay royalties after the patent expires (extending the patent's term beyond 20 years); tying a license to the purchase of unpatented products (extending the patent's scope to cover unpatented goods); requiring licenses covering patents the licensee doesn't need. The doctrine has been narrowed by Congress and courts over the past few decades — particularly by 35 U.S.C. § 271(d), which specifies certain acts that are NOT misuse — but it remains a viable defense in appropriate cases.

Morton Salt Co. v. G.S. Suppiger Co., 314 U.S. 488 (1942), is the Supreme Court case that established the modern patent misuse doctrine and is often called the foundational 'Morton Salt' precedent. The facts: Morton Salt held a patent on a machine that deposited salt tablets in canning. Morton licensed the machine to canners on condition that they buy unpatented salt tablets exclusively from Morton. Morton then sued Suppiger for infringing the machine patent. The Supreme Court held that Morton could not enforce its patent because it was using the patent to extend its monopoly to the unpatented salt tablets — conditioning access to the patented machine on buying Morton's salt tied the two together in a way that extended the patent's scope beyond the actual invention. The case established the principle that a patent holder who uses patent rights to control unpatented goods or services is not entitled to call upon courts to enforce the patent — 'the patentee has himself ... impeded the creation of a limited monopoly.' The Morton Salt doctrine was the foundation for decades of tying-based patent misuse claims. It has since been substantially narrowed by 35 U.S.C. § 271(d)(5) (enacted 1988), which provides that conditioning a patent license on purchase of another product is not misuse unless the patent holder has market power in the relevant market — restoring a market-power requirement that Morton Salt had eliminated.

Brulotte v. Thys Co., 379 U.S. 29 (1964), established that contracts requiring a licensee to pay royalties for use of patented technology after the relevant patent has expired are per se unenforceable as a matter of federal patent law — this is called the Brulotte rule. The reasoning: a patent grants a limited monopoly for 20 years; once the patent expires, the invention enters the public domain and anyone can use it freely. Requiring royalty payments for post-expiration use effectively extends the patent's monopoly beyond its statutory term, which is improper. Kimble v. Marvel Entertainment, LLC, 576 U.S. 446 (2015): the Supreme Court reconsidered and reaffirmed Brulotte, rejecting academic criticism of the rule despite acknowledging it may be economically suboptimal in some cases. The Court applied stare decisis and declined to overrule it, noting that Congress could change the rule if it wanted to. Why Brulotte matters for license drafting: (1) Any royalty provision that continues past patent expiration must be carefully analyzed — if tied to patent rights, it is voidable under Brulotte for the post-expiration period. (2) Lawful workarounds include: separate know-how, trade secret, or technology transfer licenses that genuinely provide value independently of the patent, with their own post-expiration royalty terms that are clearly attributed to those non-patent rights; royalty provisions that automatically terminate at the patent's expiration date; royalty provisions that decline after expiration (to reflect that only know-how or trade secrets, not the patent, are being licensed). (3) Pure lump-sum licenses paid before expiration are not subject to Brulotte — the doctrine applies only to installment payments or running royalties that continue post-expiration tied to use of the patented invention.

Patent misuse and antitrust law both regulate improper uses of patent rights, but they differ in important ways: (1) Standard of liability: antitrust law generally requires proof of market power, harm to competition (not just individual harm), and in many cases intent. Patent misuse historically did not require proof of market power — any patent holder who tied or required post-expiration royalties committed misuse regardless of their market position. Congress narrowed this in 1988 with § 271(d)(5) for tying arrangements (now requires market power), bringing misuse closer to antitrust for that conduct. (2) Standing and who can sue: antitrust plaintiffs must show they were injured by the anticompetitive conduct ('antitrust standing'). Patent misuse can be raised by any defendant in an infringement suit, even if they were not party to the offending arrangement and suffered no personal harm. (3) Remedies: antitrust violations can result in treble damages, attorney fees, and injunctions. Patent misuse results only in the patent being unenforceable — no damages for the misuse itself, no trebling, no attorney fees under misuse alone (though inequitable conduct might support attorney fees under 35 U.S.C. § 285). (4) Purging: antitrust injunctions can be permanent behavior modifications; patent misuse is purgeable — the patent becomes enforceable again once the offending conduct stops and the effects are unwound. (5) Scope: antitrust law requires defining a relevant market and showing competitive harm to that market; patent misuse focuses on whether the patent right itself is being extended beyond its lawful scope. The Federal Circuit has narrowed misuse toward antitrust standards — requiring anticompetitive effects in many cases — but the doctrines remain technically distinct.

Patent holders and licensors should follow several practices to avoid patent misuse: (1) Do not tie patent licenses to unpatented products unless market power is absent. Even if tying is not per se misuse post-§ 271(d)(5), it creates litigation risk and antitrust exposure. Prefer charging the full value of the patent in the royalty rate rather than through tying. (2) Terminate royalty obligations at patent expiration. License agreements should contain automatic expiration language: 'The royalty obligations hereunder shall terminate upon the expiration of the last to expire of the licensed patents.' If post-expiration payments are desired (e.g., for know-how), structure a separate know-how agreement with genuinely independent consideration, clearly identified know-how obligations, and a separate fee schedule. Do not simply extend the royalty term. (3) Do not require licenses to patents the licensee does not need, especially if those patents are unrelated to the technology the licensee is actually practicing. Mandatory portfolio licenses where the essential patents have market power may constitute misuse and trigger antitrust review. (4) Do not use patent rights to control how licensees use or dispose of products after authorized sale — patent exhaustion limits post-sale restrictions to contract law, not patent law. Attempting to enforce post-sale restrictions through patent infringement suits after Impression Products v. Lexmark is not just misuse but legally incorrect. (5) Ensure royalty bases are tied to the patented technology — avoid computing royalties on clearly unpatented components without a strong market-value nexus. (6) Conduct periodic licensing audits — misuse can arise from course of conduct over time, not just a single agreement. Review existing license agreements for post-expiration royalty provisions, tying elements, and mandatory package components before they are raised as defenses in litigation.