Courts and litigants alike have struggled to make sense of claim vitiation, the idea that reading a claim element to encompass an accused product would so stretch the claim language as to “vitiate” (i.e., make ineffective) that claim element. Claim vitiation has been invoked as an exception to the judicially created doctrine of equivalents, which allows courts to find infringement even though a claim element is not literally present in the accused product. Over the past year, however, the Federal Circuit has emphasized that claim vitiation is not an exception to the doctrine of equivalents, but merely a finding under the doctrine of equivalents test.
Under the doctrine of equivalents, an accused product can be found to infringe a claim where an “equivalent” of the claimed feature is present in the accused product. There are a number of tests for determining what an “equivalent” is, perhaps the most common of which is to ask whether the allegedly equivalent feature of the accused product performs substantially the same function in substantially the same way to achieve the same result as the claimed element (i.e., the “function-way-result test”).
A common argument for defendants in patent infringement suits is that where a finding of equivalence would so stretch the claim language as to “read out” a claim limitation, the doctrine of equivalents is precluded because its application would cause the claim limitation to be “vitiated.” The use of this argument has generated significant confusion and has effectively caused the doctrine of claim vitiation to take on a life of its own apart from the doctrine of equivalents.
However, over the course of the past year, the Federal Circuit has attempted to rein in and clarify the use of claim vitiation as an argument against noninfringement. In three opinions issued since December 2012—Deere & Co. v. Bush Hog, LLC, Brilliant Instruments, Inc. v. GuideTech, LLC, and The Charles Machine Works, Inc. v. Vermeer Manufacturing Co.—the Federal Circuit overturned a finding of non-equivalence based on claim vitiation in each decision. In all three cases, the Federal Circuit reiterated earlier case law explaining that vitiation is merely “a legal determination that the evidence is such that no reasonable jury could determine two elements to be equivalent.” It does not allow the court to bypass the traditional equivalence analysis, for example using the function-way-result test. Also drawing from pre-existing case law, the Federal Circuit clarified what claim vitiation is not—it is not an exception to the doctrine of equivalents and “cannot be satisfied by simply noting that an element is missing from the claimed structure or process.”
Although these cases do not actually change the law on claim vitiation, they help to clarify that claim vitiation can be used as an evidentiary bar to preclude the question of equivalence from reaching a jury. It cannot, however, preclude a court from performing an infringement analysis under the doctrine of equivalents. It is unclear how high the bar is set, but what is clear is that claim vitiation does not allow defendants in patent infringement suits to simply posit that applying the doctrine of equivalents would “vitiate” a claim limitation. Instead, any argument that claim language is vitiated must be supported by traditional arguments for finding non-equivalence.
This advisory was prepared by Nutter's Intellectual Property practice. For more information, please contact your Nutter attorney at 617.439.2000.
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