Patent Infringement Defenses

What is the difference between non-infringement and invalidity defenses?

Non-infringement and invalidity are both defenses to patent infringement claims, but they have fundamentally different effects and legal standards: Non-infringement means: the accused product or process does not fall within the scope of the patent claims as properly construed. Even if the patent is perfectly valid, the defendant wins on non-infringement if their product doesn't meet every element of any asserted claim. Non-infringement is a claim-by-claim finding — some claims may cover the accused product and others may not. Invalidity means: the patent claims are legally defective and should not have been granted — either because the invention was anticipated by prior art (§ 102), obvious over prior art (§ 103), or the claims don't satisfy formal requirements (§ 112 written description, enablement, definiteness). Invalidity is also claim-by-claim — courts can find some claims invalid and others valid. Key differences: (1) Burden of proof: invalidity must be proven by clear and convincing evidence (Microsoft v. i4i, U.S. 2011) — a higher standard than preponderance. Non-infringement is a preponderance question once the plaintiff establishes infringement. (2) Effect on the patent: a non-infringement finding means the defendant doesn't owe damages, but the patent remains valid and can be asserted against others. An invalidity finding cancels the claims as to everyone — a much stronger protection for the accused infringer and the industry. (3) Strategic interaction: when a defendant wins on non-infringement, the plaintiff may redesign the accused product. When a defendant wins on invalidity, the patent cannot be reasserted against anyone. This is why accused infringers almost always raise both defenses — a 'belt and suspenders' approach.

What is the clear and convincing evidence standard for patent invalidity?

Patents carry a statutory presumption of validity under 35 U.S.C. § 282 — once the USPTO issues a patent, it is presumed valid. To overcome this presumption and invalidate a patent, a challenger (typically an accused infringer in litigation) must present clear and convincing evidence — a higher standard than the preponderance of the evidence standard (more likely than not) used in most civil litigation. Clear and convincing evidence was confirmed by the U.S. Supreme Court in Microsoft Corp. v. i4i Limited Partnership (2011). The Court rejected Microsoft's argument that the standard should be reduced to preponderance when challenging invalidity based on prior art the USPTO never considered. This means: even if a defendant finds prior art that appears to anticipate or render obvious the patent claims, they must present that evidence so clearly and convincingly that the jury or judge has an 'abiding conviction' that the claim is invalid. The standard is higher when: the same prior art was considered by the USPTO during examination (the examiner's judgment that the art didn't invalidate the claim gets deference); the evidence relies primarily on documentary prior art that the USPTO already reviewed. The standard may be easier to meet when: the prior art was never presented to the USPTO; the invalidity theory is based on a factual determination (e.g., a prior public use) rather than an obviousness combination the examiner had considered. In IPR/PGR at the PTAB: the standard is different — challengers prove invalidity by a preponderance of the evidence (not clear and convincing). This is one reason IPR petitions are often preferred over district court invalidity challenges for clearing out bad patents.

What is patent exhaustion and how does it work?

Patent exhaustion (also called the 'first sale doctrine') is a doctrine that limits the scope of a patent owner's rights after an authorized sale of a patented item. Under the patent exhaustion doctrine, once a patentee (or its authorized licensee) makes an authorized sale of a patented article, the patent rights with respect to that particular article are 'exhausted' — the buyer can use, resell, or repair the article without patent infringement, even if doing so would otherwise read on the patent claims. Key cases: Impression Products, Inc. v. Lexmark International (U.S. 2017) — the Supreme Court held that: (1) patent exhaustion applies to ALL authorized sales, including sales of cartridges with 'single use' restrictions (the restriction may be enforceable as a contract matter, but not as a patent infringement claim after exhaustion); (2) patent exhaustion applies to authorized sales anywhere in the world, including foreign sales — overruling the Federal Circuit's rule that only domestic sales triggered exhaustion. Bowman v. Monsanto (U.S. 2013) — patent exhaustion does NOT cover 'making' new articles (soybeans) from the patented article. A purchaser can use but not replicate. Repair vs reconstruction: a purchaser can repair an exhausted patented item (allowed) but cannot reconstruct it from components (not allowed). The distinction is fact-specific: was the item truly spent? Did the reconstruction recreate the claimed inventive concept? Exhaustion is a defense to patent infringement claims — it does not prevent the patentee from enforcing contract provisions (breach of contract claims for 'single use' restrictions may still survive).

What is prior user rights under § 273?

Prior user rights (35 U.S.C. § 273) is a statutory defense available to a defendant who was commercially using a claimed invention before the patent was filed. The defense was strengthened by the AIA (Leahy-Smith America Invents Act, 2011). Requirements for § 273 defense: (1) Subject matter: the defendant must have commercially used or reduced to practice the specific subject matter that became the basis for the patent claim asserted against them. Pre-AIA § 273 applied only to business method patents; post-AIA § 273 applies to any machine, manufacture, composition of matter, process, or method of manufacturing. (2) Timing: the commercial use must have begun more than 1 year before the earlier of: (a) the effective filing date of the application that issued the patent; or (b) the date of any public disclosure triggering a grace period. (3) Commercial use: mere laboratory testing or research does not qualify — the use must be in connection with actual commercial activity (internal use in a manufacturing process counts even if not sold externally). Important limitations: (a) The § 273 defense is personal — it belongs to the entity that practiced the prior use and cannot be transferred except as part of a sale of the entire business unit in which the use occurred. This prevents defendants from buying prior user rights. (b) Prior user rights do not invalidate the patent — they only protect the specific defendant in the specific context of their prior use. (c) A party claiming prior user rights cannot expand the scope of their protected use beyond what they were practicing before the patent's effective filing date. (d) University research exception: § 273(e)(5) — the defense is not available against a patent owned by or licensed to a university. Strategic use: § 273 is particularly valuable for manufacturers who developed proprietary processes or methods that they kept as trade secrets — if someone later patents a similar invention, the trade secret holder can raise § 273 without needing to prove invalidity.

What is inter partes review (IPR) and how is it different from invalidity in litigation?

Inter Partes Review (IPR) is a post-grant USPTO proceeding before the Patent Trial and Appeal Board (PTAB) in which a petitioner can challenge the validity of an issued patent on prior art grounds (§§ 102, 103). IPR was created by the AIA (2012) and is the most commonly used post-grant invalidity challenge. How IPR differs from district court invalidity: (1) Standard of proof: IPR requires only preponderance of the evidence (more likely than not), versus clear and convincing evidence in district court. This is a lower bar and makes it significantly easier to invalidate claims at the PTAB than in court. (2) Claim construction: PTAB uses the Phillips standard (as of 2018 rulemaking) — the same as district courts. (3) Scope: IPR is limited to prior art challenges (§§ 102 and 103 based on patents and printed publications). IPR cannot challenge based on § 101 (subject matter eligibility), § 112 (enablement, written description, definiteness), or § 102 public use/on-sale bars. PGR (Post-Grant Review, within 9 months of grant) can raise any invalidity ground. (4) Estoppel: an IPR petitioner who gets a final written decision is estopped from raising in district court any ground the petitioner raised or 'reasonably could have raised' in the IPR — a significant limitation. Defendants typically file IPR as a parallel track while district court litigation proceeds. (5) Cost: IPR petitions typically cost $200,000–$500,000 in attorney fees versus $3M–$10M+ for full patent litigation. (6) Speed: PTAB must issue a final decision within 12 months of institution — faster than district court litigation. Timing: IPR must be filed within 1 year of service of a complaint for patent infringement — missing this deadline is a common strategic pitfall. IPR institution rate: the PTAB institutes review in approximately 60–65% of petitions; when instituted, approximately 70–75% of challenged claims are cancelled.