Overview Edit

The doctrine of equivalents is a judicially-created theory for finding patent infringement when the accused process or product falls outside the literal scope of the patent claims. The essential objective inquiry is: “Does the accused product or process contain elements identical or equivalent to each claimed element of the patented invention?”

As the U.S. Supreme Court recognized in its Festo opinion,[1] the doctrine raises issues of claim transparency that affect the public:

This clarity [of patent boundaries] is essential to promote progress, because it enables efficient investment in innovation. A patent holder should know what he owns, and the public should know what he does not.[2]

The doctrine of equivalents, however, “renders the scope of patents less certain. . . . If competitors cannot be certain about a patent’s extent, they may be deterred from engaging in legitimate manufactures outside its limits, or they may invest by mistake in competing products that the patent secures.”[3] The Federal Circuit in Festo gave these considerations precedence, emphasizing the notice value of claims in finding a complete bar to application of the doctrine of equivalents to claim elements narrowed during the course of a prosecution.[4] The Supreme Court ultimately softened the appellate court’s ruling, however, making the bar a matter of rebuttable presumption.[5]

References Edit

  1. Festo Corp. v. Shoketsu Kinzoku Kogyokabushiki Co., 535 U.S. 722 (2002)(full-text).
  2. Id. at 730-31.
  3. Id. at 732.
  4. See Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 234 F.3d 558, 574-78, 56 U.S.P.Q.2d (BNA) 1865 (Fed. Cir. 2000)(full-text) (emphasizing the notice function of claims).
  5. 535 U.S. at 737-41. The Court reasoned that a complete bar in these circumstances would exceed the inferences that courts reasonably can draw from a narrowing amendment and would “disrupt the settled expectations of the inventing community.” Id. at 737-39. It sought to strike the appropriate balance by placing the burden of proof on the patentee to show why an amendment does not surrender the particular equivalent in question. Id. at 739-41.

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