Gideon Korrell Analyzes 5 Court Findings That Reinforce the Power of Precise Patent Language

1. Gideon Korrell • Analyzes 5 Court Findings That Reinforce the Power of Precise Patent Language

2. In a pivotal ruling, the Federal Circuit overturned the Patent Trial and Appeal Board’s (PTAB) interpretation of a key transitional phrase in Eye Therapies, LLC v. Slayback Pharma, LLC. The case turned on how the phrase “consisting essentially of” was interpreted in U.S. Patent No. 8,293,742, which claims a method for reducing eye redness using brimonidine. The decision highlights the critical role of precise claim language, especially when shaped by prosecution history. • Gideon Korrell examines the five key court findings from the case that underscore the lasting impact of exact wording in patent law:

3. The Federal Circuit emphasized that prosecution statements can override the typical meaning of transitional phrases. While “consisting essentially of” usually allows for unlisted ingredients that don’t materially change the invention, Eye Therapies explicitly argued, during prosecution, that no additional active ingredients were included. The court treated these statements as binding disclaimers, showing that claim scope can be redefined by applicant remarks. • 1. PROSECUTION HISTORY NARROWS CLAIM SCOPE

4. 2. CLAIM LANGUAGE IS INTERPRETED IN CONTEXT • Despite the broader default interpretation, the court held that the phrase “consisting essentially of brimonidine” meant brimonidine alone, based on how the applicant used the term during prosecution. The use of definitional language, such as “i.e.” to equate the claim with single-agent treatment, played a decisive role. Gideon Korrell notes that such language creates clarity but also locks in the meaning.

5. 3. NOT ALL EMBODIMENTS CONTROL CLAIM CONSTRUCTION • The PTAB relied on specification examples that included combinations of brimonidine with other agents. But the Federal Circuit clarified that claims don’t need to cover every disclosed embodiment, especially when later amendments were made to overcome prior art. Here, narrowing language during prosecution overrode broader disclosures in the specification.

6. Because the PTAB used a broader interpretation of the claim, it wrongly found the claims obvious based on prior art references that involved combinations of active ingredients. The Federal Circuit vacated that conclusion. Under the correct interpretation, limited to brimonidine alone, those references no longer qualified. As Korrell explains, a shift in claim scope can fundamentally alter the outcome of an obviousness challenge. • 4. OBVIOUSNESS ANALYSIS MUST ALIGN WITH CLAIM CONSTRUCTION

7. 5. TRANSITIONAL PHRASES CAN BE REDEFINED • While transitional phrases like “comprising,” “consisting of,” and “consisting essentially of” are usually treated as having standard meanings, this case confirms they are not immune to redefinition. When applicants use precise language and make limiting arguments during prosecution, courts will hold them to it. Gideon Korrell stresses that this should prompt practitioners to think strategically about every word during patent drafting and amendment.

8. FINAL THOUGHT FROM GIDEON KORRELL • This case is a wake-up call for both patent prosecutors and litigators. What’s said during prosecution isn't just temporary persuasion, it becomes part of the patent's DNA. Precision matters. In patent law, a single phrase can define the outcome of litigation years later.

9. THANK • YOU