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May 15, 2019Blog

Future Trends on the Doctrine of Equivalents?

Claims of infringement under the doctrine of equivalents routinely accompany literal infringement claims in patent infringement litigation.  Likewise, patent prosecutors typically try to avoid narrowing the scope of equivalents during prosecution of a patent application.  But, a pair of recent decisions from the Federal Circuit may keep some wondering why all of the fuss.

Under the doctrine of equivalents, a product or process that does not literally infringe may nonetheless be found to infringe if there is “equivalence” between the elements of the accused product or process and the claimed elements of the patented invention.  Equivalence is frequently determined under the “function-way-result” test (i.e., whether the accused product performs substantially the same function in substantially the same way to obtain the same result) or the “insubstantial differences” test (i.e., whether the accused product or process is substantially different from what is patented).

Earlier this year in Duncan Parking Techs., Inc. v. IPS Group, Inc., the Federal Circuit affirmed summary judgment of noninfringement, both literal and under the doctrine of equivalents (“DOE”), of U.S. Patent No. 7,854,310.  In doing so, the Court seemed to breathe renewed life into the vitiation rule.  Vitiation precludes the DOE from extending so broadly as to essentially void a claim limitation, although its applicability in recent years has faded considerably.  The ’310 patent claims a credit card-enabled, solar-powered parking meter, including a cover panel with a plurality of buttons that is part of a housing for the meter.  In contrast, the keypad of Duncan’s accused product is an extension of the electronic parking meter device that is housed in the housing.  IPS argued that changing the location of the buttons from the cover panel to the device itself is an insubstantial change, but the Court was not persuaded.  Instead, the Court found that the accused product does not work in the same way as the claimed invention.  In doing so, the Court repeatedly highlighted that the DOE cannot be used to read out or erase a claim limitation on which the public is entitled to rely.  And in the Court’s view, a finding of equivalence in this case would vitiate the claim limitation requiring the claimed buttons to be located on the cover panel, which is a part of the housing, not the device.

More recently, in Amgen Inc. v. Sandoz Inc., the Federal Circuit took an opportunity to remind the bar that:

“[t]he doctrine of equivalents applies only in exceptional cases and is not ‘simply the second prong of every infringement charge, regularly available to extend protection beyond the scope of the claims.’”

In particular, Amgen sued Sandoz for patent infringement over Sandoz’s biosimilar versions of Amgen’s biologic products used for treating neutropenia, a deficiency of white blood cells resulting from chemotherapy.  One of the asserted patents, U.S. Patent No. 8,940,878, required a multi-step process for purifying proteins, including a series of separate process steps (i.e., “refolding,” “washing,” and “eluting”) performed by adding discrete solutions to a separation matrix in sequence.  Sandoz’s accused process, however, only uses one step (i.e., applying the refold solution to the matrix, with no separate washing or eluting steps) and one solution.  Amgen tried to argue that Sandoz’s one-step, one-solution process achieves the same functions (washing and eluting), in substantially the same way (binding protein preferentially compared to contaminants, and then raising salt concentration to reverse protein binding) to achieve the same result (protein purification).  The Court, however, rejected Amgen’s DOE argument because it required overriding the natural claim language to cover any method of using a salt concentration gradient in an adsorbent matrix to separate a protein of interest.  Rather, the Court found that Sandoz’s one-step, one-solution process accomplishes purification in a different way from the claimed method, and thus is not equivalent.

The Court’s stark pronouncement regarding “exceptional cases” in Amgen is likely not intended to signal a new standard for DOE.  However, underlying the Court’s decision is the same concern expressed in Duncan – the public has a right to rely on the language of patent claims in avoiding infringement.  Both of these cases serve as helpful reminders of this principal concern that often restricts application of the DOE to expand claim scope.

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