CAFC Precedential - 2025 - Claim Construction - Prosecution disclaimer

In Azurity Pharmas v. Alkem Labs., the Federal Circuit held that Azurity clearly and unmistakably surrendered claim scope covering any presence of propylene glycol by inserting “consisting of” the list of ingredients to avoid prior art wherein propylene glycol was used as a stabilizer, even though th list of ingredients included a flavoring agent. Because the accused device included a flavoring agent containing propylene glycol it was non-infringing.

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In Barrette Outdoor Living v. Fortress Iron, the Federal Circuit affirmed noninfringement based broadly construing “boss” not necessarily fastener-less, despite the patent's discussion of multiple advantages of fastener-less bosses. The court held that a patent's discussion of multiple advantages does not justify importing one advantage-related feature into claims absent absent clear and unmistakable disclaimer; here, criticism of fastener-based prior art did not clearly limit “boss” to fastener-less structures.

Stated the court: “a]statement made during prosecution of related patents may be properly considered in construing a term common to those patents, regardless of whether the statement pre- or post-dates the issuance of the particular patent at issue“ (citing Teva Pharms. ¹⁾.

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In Eye Therapies v. Slayback Pharma, the Federal Circuit relied on prosecution history statements accompanying an amendment define the scope of “consisting essentially of,” treating explanatory remarks and definitional “i.e.” usage as limiting. The court held that although “consisting essentially of” is typically semi-open, the intrinsic record can assign it an atypically restrictive meaning; here, the prosecution history establishes that the phrase excludes use of active ingredients other than brimonidine in the claimed methods. When the applicant uses “i.e.” to equate a claim phrase with a particular meaning in prosecution arguments, that usage is strongly definitional and supports construing the claim phrase consistently with the stated definition. Where claims were narrowed during prosecution, claims need not cover every described embodiment.

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In Focus Products Group Internat'l v. Kartri Sales Co., the Federal Circuit reversed the District Court for the Southern District of NY based on corrected claim scope for a shower curtain ring. The court held that prosecution history, including restriction and an election to withdraw nonelected species, and prosecution of a divisional application excluding the elected species can constitute clear and unmistakable disclaimer of the claim scope. Here, because the properly construed claims exclude a feature present in the accused product (i.e., rings with flat upper edges) summary judgment of infringement cannot stand and must be reversed as to the party preserving the noninfringement issue.

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In Maquet Cardiovascular v. Abiomed, the Federal Circuit reversed and remanded to the district court's claim construction claims with added negative limitations. The court held that prosecution disclaimer from a related patent's prosecution is relevant only when the earlier prosecution addresses a limitation in common with the claim term being construed; material differences in claim language (e.g., claiming an “entire elongate lumen distal to” a component versus a “guide mechanism comprising a lumen”) defeat reliance on that history to import a negative limitation.

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In Restem v. Jadi Cell, the Federal Circuit held that clear examiner statements characterizing the allowed claim scope, coupled with applicant acquiescence during prosecution, can narrow claim scope (here, to a “cell population”), and that narrowed understanding may control over broader specification disclosures/definitions.

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