Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd. case brief

Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd. case brief summary
535 U.S. 722 (2002)

CASE SYNOPSIS

Certiorari was granted to the United States Court of Appeals for the Federal Circuit to review a judgment for the defendant competitor on the plaintiff patentee's claim of patent infringement. The United States Court of Appeals for the Federal Circuit had held that by narrowing a claim to obtain a patent under 35 U.S.C.S. § 112, the patentee surrendered all equivalents to the amended claim element.

CASE FACTS
The competitor's device did not fall within the literal claims of the patents, but the patentee argued it was so similar that it infringed under the doctrine of equivalents.


DISCUSSION

• The United States Supreme Court held that prosecution history estoppel arose when an amendment was made to secure the patent and it narrowed the patent's scope. 
• If a § 112 amendment was truly cosmetic, then it would not narrow the patent's scope or raise an estoppel. 
• If a § 112 amendment was necessary and narrowed the patent's scope -- even if only for a better description -- estoppel could apply. 
• The patentee had the burden of proving that an amendment was not made for a reason that would give rise to estoppel, and also had the burden of showing that the amendment did not surrender the particular equivalent in question. 
• As the amendments were made for a reason relating to patentability, the question was not whether estoppel applied but what territory the amendments surrendered. 
• Estoppel did not effect a complete bar. 
• The question remained whether the patentee could show that the narrowing amendments did not surrender the equivalents at issue. 
• Those matters were to be determined by further proceedings below.

CONCLUSION
The judgment was vacated and remanded.

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