Wilson Sporting Goods Co. v. David Geoffrey & Assocs. - 904 F.2d 677 (Fed. Cir. 1990)

Rule:

Infringement may be found under the doctrine of equivalents if an accused product performs substantially the same overall function or work, in substantially the same way, to obtain substantially the same overall result as the claimed invention. Even if this test is met, however, there can be no infringement if the asserted scope of equivalency of what is literally claimed would encompass the prior art. This issue of whether an asserted range of equivalents would cover what is already in the public domain is one of law, which the appellate court reviews de novo. The jury is presumed to have resolved underlying evidentiary conflicts in plaintiff's favor.

Facts:

Plaintiff Wilson Sporting Goods Co. and defendant Dunlop Slazenger Corporation manufactured and sold golf balls. Plaintiff had a patent on its dimple design. Plaintiff sued defendant for infringement, alleging that its golf balls infringed on plaintiff's patent. The magistrate judge entered judgment for plaintiff after a jury found plaintiff's patent valid and that defendant willfully infringed the patent. Defendant challenged the decision.

Issue:

Under the circumstances, could defendant be held liable for patent infringement?

Answer:

No.

Conclusion:

The court of appeals noted that a patentee should not be able to obtain, under the doctrine of equivalents, coverage that he could not lawfully have obtained from the Patent and Trademark Office (PTO) by literal claims. The doctrine of equivalents existed to prevent a fraud on a patent, not to give a patentee something which he could not lawfully have obtained from the PTO had he tried. Thus, since prior art limited what an inventor could have claimed, it would limit the range of permissible equivalents of a claim. In the case at bar, the court held that the magistrate erred in denying defendant's motion for judgment notwithstanding the verdict on infringement because, as a matter of law, a range of equivalents broad enough to cover the allegedly infringing product would also have encompassed the prior art.