Gideon Korrell Analyzes 5 Court Findings That Reinforce the Power of Precise Patent Language
                     Gideon 
AnaKlyozersr 5e Court Findings That Rlelinforce 
the Power of Precise 
Patent Language
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:
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 
1. PROSECUTION materially change the invention, Eye Therapies 
HISTORY explicitly argued, during prosecution, that no 
additional active ingredients were included. The 
NARROWS court treated these statements as binding 
CLAIM SCOPE disclaimers, showing that claim scope can be 
redefined by applicant remarks.
2. CLAIM 
LANGUAGE IS 
INTERPRETED IN 
DCesOpitNe thTe EbroXadTer 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.
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.
4. OBVIOUSNESS Because the PTAB used a broader 
ANALYSIS MUST interpretation of the claim, it wrongly found 
ALIGN WITH CLAIM the claims obvious based on prior art 
references that involved combinations of 
CONSTRUCTION
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.
5. TRANSITIONAL While transitional phrases like 
PHRASES CAN BE “comprising,” “consisting of,” and “consisting essentially of” are 
REDEFINED 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.
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.
THAN
KYO U