High Court Broadens Scope Of Potential Patent Infringements

In a unanimous decision authored by Justice Kennedy, the U.S. Supreme Court today made it easier to demonstrate patent infringement by holding the "doctrine of equivalents" may properly apply to claims modified during the application process.

"In the decision now under review the Court of Appeals for the Federal Circuit held that by narrowing a claim to obtain a patent, the patentee surrenders all equivalents to the amended claim element. ... There are some cases, however, where the amendment cannot reasonably be viewed as surrendering a particular equivalent. The equivalent may have been unforeseeable at the time of the application; the rationale underlying the amendment may bear no more than a tangential relation to the equivalent in question; or there may be some other reason suggesting that the patentee could not reasonably be expected to have described the insubstantial substitute in question. In those cases the patentee can overcome the presumption that prosecution history estoppel bars a finding of equivalence."

The prinicples involved in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd. are dense and procedural, but the bottom line of today's decision is that non-identical copies of a patented device are viable infringement targets, even where (as is commonly the case) the patent claim was amended during the give and take between the applicant and the USPTO leading up to the patent's issuance. The Federal Circuit's prior opinion, now vacated, had curtailed such claims.

Related links:
Opinion (.pdf, via the Court)
Opinion (html, via FindLaw)
Stories from Reuters, The Nando Times, CNN, Newsday (from January; good discussion of broader implications of the case)
(Eagle-eyed Katie blogged the reversal.)
--Later: more from Howard and Stephan.