EPOS Technologies v. Pegasus Technologies

Scott Daniels | September 10, 2014

September 5, 2014

Panel: Hughes and Bryson. Opinion by Hughes.


The Doctrine of Equivalents is applicable in cases where the accused product or process does not literally meet one or more of the limitations of the patent-in-suit.  Essentially, a court asks whether the accused product or process possesses a feature(s) which is the equivalent of the limitation(s) not literally met.

Legal Standards for Determining Equivalence

There are two alternative traditional methods for assessing whether an accused product of process has an equivalent to the unmet limitation.

First, does the asserted equivalent perform substantially the same function, in substantially the same way, to accomplish substantially the same result?  If so, the limitation is satisfied.  The second, and simpler method, is to ask whether the difference between the unmet claim limitation and the feature asserted to be equivalent, is trivial or non-trivial?

Both approaches entail substantial factual enquiries, typically requiring information that becomes fully available only at trial.  Accordingly, it is often difficult to write an opinion for clients, on the issue of equivalence.

Legal Shortcuts for Avoiding the Equivalence Issue

There are five legal theories that allow one to sidestep the doctrine of equivalents.

  • The Festo Exception – there is no infringement by equivalence where the claim limitation in question was the subject of a narrowing amendment or argument during prosecution, that amendment or argument being related to patentability. But remember to consider the three exceptions to the Festo
  • Hypothetical Claim Analysis – the CAFC’s Wilson decision allows a court to create a hypothetical claim that encompasses the feature asserted to be equivalent, and then to determine whether the hypothetical claim would be anticipated by or obvious over the prior. If so, the doctrine of equivalents does not apply.
  • Disclosure-Dedication Doctrine – where the specification discloses the feature asserted to be equivalent, and the claim does not encompass it, the courts find that the doctrine of equivalents does not apply – the patentee by disclosing, but not claiming the feature asserted to be equivalent, has dedicated that feature to the public.
  • Claim Vitiation – some claim limitations are binary, that is, they define only two options, one within the scope of the claims and one outside. The “majority” requirement of the claims in the CAFC’s Moore decision is a good example, the accused product involved a “minority,” and the court found that there could be no equivalence because a finding that minority was equivalent to majority would have the effect of reading the limitation entirely out of the claim.
  • All Advantages Rule – the doctrine of equivalents does not apply where the specification of the asserted patent touts the importance of the function of the feature asserted to be equivalent.

EPOS Technologies

The trial court granted summary judgment that the patents-in-suit were not infringed.  For four of the patents, which do not interest us here, the CAFC reversed the summary judgment because the trial court had construed the claims too narrowly and remanded the case.  For the remaining patent, which does interest us, the CAFC found that the court had incorrectly analyzed the doctrine of equivalents.

The patent claimed a digital pen.  All the claims recited a handheld device for use with a board comprising several components, including an ultrasonic receiver or transmitter device for receiving or transmitting an “intermittent” ultrasound signal.  Since, the corresponding signal of the accused pen was continuous, the trial court applied the Moore claim vitiation doctrine, to find that there could be no infringement under the doctrine of equivalents – finding continuous to be equivalent would read the limitation out of the claim.

The CAFC reversed, finding that the trial court’s analysis was too brief and sending the case back to the judge.  The appellate court then cautioned that “[c]ourts should be cautious not to shortcut this inquiry by identifying a ‘binary’ choice in which an element is either present or ‘not present.’”  It added that the trial court had failed to consider all the evidence of record.


The Moore claim vitiation notion may have slipped from being a doctrine into being a notion.

The other legal shortcuts may also be less reliable than previously thought.

Full Opinion

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