Doctrine of Equivalents at the Federal Circuit

By Dennis Crouch

When I wrote about the Doctrine of Equivalents (DOE) yesterday, I made a mental note that the Federal Circuit has not decided many DOE cases recently. To confirm this notion, I searched Westlaw for all Federal Circuit decisions that mention the “Doctrine of Equivalents.” Those results are presented below:



  • Of course, a decision's mention of the words "doctrine of equivalents" does not suggest that the appellate decision involved the DOE. However, the majority of these cases did at least involve allegations of infringement under the DOE.   
  • The rise in the late 1990’s and early 2000’s revolves around Festo.
  • For the past decade, the number of Federal Circuit patent infringement appeals has remained relatively steady.
  • To find the number of reported patent decisions, I searched Westlaw’s database of Federal Circuit decisions for the terms “patent /2 (infring! valid! invalid! obvious!)”.
  • These results continue the trends discussed in Allison & Lemley’s 2007 article “The (Unnoticed) Demise of the Doctrine of Equivalents.” and Lee Petherbridge’s excellent 2008 article “The Claim Construction Effect.”

6 thoughts on “Doctrine of Equivalents at the Federal Circuit

  1. 6

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  2. 5

    Malcolm – not sure if your comment just belongs to a different thread, or if this is one of your stunning non sequitur moments…

  3. 4

    It’s true. Dyk’s dissent is a distraction from the newsworthy fact that it’s been quite a while (or seems it) since the scope of a class of biotech patents have been strengthened/expanded in this manner. I would not have predicted the result here and frankly I’m skeptical that the case will turn out to be broadly applicable.

  4. 3

    Fiber: I think that there are two primary explanations for the decrease. (These are more fully developed in the articles that I cited above).

    First, it is now seemingly more difficult to win a DOE case because of strict application of the all-elements rule, prosecution history estoppel, and vitiation.

    Second, the primacy of claim construction issues have put DOE in the back-seat.

  5. 2

    why the decrease?

    link to

    The Festo decision in 2002 eliminated DOE as an option in all but those rare cases where the element in dispute was not amended during prosecution in a narrowing manner. DOE died on that day. This is news?

  6. 1

    So everyone proceeds with literal and then decides not to bother with asserting DOE? Of course this illustrates my lack of knowledge in this area, but during markman can you get a construction under literal and the DOE? I guess my point is why the decrease?

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