Prosecution History Estoppel: Navigating Limits On Equivalents In Patent Litigation

The Highlights

1. Prosecution history estoppel can significantly limit reliance on the doctrine of equivalents: While patentees may seek to capture non‑literal infringement through equivalence arguments, amendments or statements made during prosecution can bar that approach by signaling a surrender of claim scope.
   
   
2. Both claim amendments and prosecution arguments can create estoppel: Estoppel is not limited to narrowing amendments made for patentability; clear and unequivocal statements distinguishing prior art can also constrain claim scope in later litigation—sometimes unintentionally.
   
   
3. Prosecution decisions have lasting litigation consequences: The article underscores the importance of strategic prosecution drafting and argumentation, as early choices can determine infringement outcomes, settlement leverage, and enforcement flexibility years later.