Federal Circuit applies Festo to prosecution history Cases of Interest >  IP >  Patent >  Claim Interpretation >  Prosecution History Estoppel

Primos v Hunter's Specialties


In a Federal Circuit opinion, the court applied the Festo case in order to determine whether a patentee was estopped from claiming equivalents.

The equivalent at issue was whether a "dome" was equivalent to a "plate" in a hunting call. During prosecution, two amendments were made that related to patentability:
  • That the plate have a length
  • That plate be differentially spaced above a membrane

The appeals court agreed with the district court that:
  • All plates would have length, so that would not affect equivalents
  • The differential spacing was added to overcome prior art where a plate was set at fixed spacing above a membrane

Because the accused device had the differential spacing, there was no reason to limit equivalents as to that feature, and the jury was allowed to consider whether a dome could be equivalent to a plate. The jury's verdict of infringement was affirmed.

This is a seemingly simple but important case in claim construction and prosecution history estoppel, and it shows the mechanics of the Supreme Court's ruling in Festo. After decisions like this one, where an amendment to one part of a claim has nothing to do with the alleged equivalent, courts will be less likely to find prosecution history estoppel.

Further commentary at Patently-O (cache)


Attached files

ID Name Comment Uploaded Size Downloads
19 051001p[1].pdf Opinion Michael Risch Wed 14 of Jun, 2006 18:59 GMT 135.87 Kb 4538
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