Question 20
Domain 5: Patent Ownership, Infringement, and EthicsWhat is the legal effect of a prosecution history disclaimer?
Correct answer: B
Explanation
A prosecution history disclaimer narrows claim scope when the patentee clearly and unmistakably disavows subject matter during prosecution. Courts treat those statements as limiting the claims, so the patent cannot later be read to cover what was surrendered.
Why each option is right or wrong
A. It expands the scope of the claims
B. It limits the scope of the claims based on statements made during prosecution
Under U.S. patent claim-construction doctrine, statements made to the USPTO during prosecution can operate as a disclaimer when they are clear and unmistakable, and the court then construes the claims in light of that surrender. The effect is to exclude the disclaimed subject matter from the claim’s reach, so the patentee cannot recapture it later through litigation positions; this is a judicially created limitation applied during claim construction, not a separate statutory amendment to the claims.
C. It creates new prior art
D. It allows the examiner to reject additional claims