Regents of the University of Minnesota v. AT&T Mobility LLC

Background

Regents of the University of Minnesota alleged that AT&T Mobility LLC, Sprint Solutions, Inc., Sprint Spectrum L.P., T-Mobile USA, Inc., and Cellco Partnership d/b/a Verizon Wireless infringed five patents. Ericsson, Inc., Nokia of America Corp., and Nokia Solutions and Networks US LLC participated as intervenor defendants in the cases identified in the caption.

The opinion addresses two Linear Precoding Patents: U.S. Patent No. 7,251,768 and reissue patent RE45,230. The patents concern digital coding techniques for transmitting data. The patented process includes encoding, interleaving, and mapping data. The accused technology adds a scrambling step between interleaving and mapping.

The court had previously determined that the defendants did not literally infringe the Linear Precoding Patents because of the additional scrambling step. Regents then relied on the doctrine of equivalents, which can support infringement when an accused feature is not literally the same as the claimed feature but differs only insubstantially.

Motion and Standard

The defendants moved for summary judgment of non-infringement under the doctrine of equivalents. Summary judgment is appropriate when there is no genuine dispute over a material fact and the moving party is entitled to judgment as a matter of law. The court considered the defendants’ three proposed defenses as legal questions.

Prosecution History Estoppel

Prosecution history estoppel can prevent a patent owner from using the doctrine of equivalents for subject matter surrendered during the patent-approval process. The defendants argued that Regents’ amendments to the ’768 patent, and amendments made during reissuance of the ’230 patent, surrendered any intermediate step—such as scrambling—between interleaving and mapping.

The court held that prosecution history estoppel applied to both patents and presumed that Regents had surrendered subject matter between the original and amended claim language. But the court found that Regents overcame that presumption under the exception for an amendment whose reason bears only a tangential relationship to the accused equivalent.

The prosecution history showed that Regents added the interleaver and mapper to fill gaps in the independent claims, using subject matter that had appeared in dependent claims. The court concluded that the amendments did not show an intent to exclude other intermediate steps, including a scrambler. It therefore held that prosecution history estoppel did not bar Regents’ doctrine-of-equivalents theory.

Disclosure Dedication

Under the disclosure-dedication doctrine, material disclosed in a patent but not claimed may be treated as dedicated to the public and unavailable for recapture through the doctrine of equivalents. The defendants argued that Regents dedicated a scrambling step to the public by discussing or incorporating the HIPERLAN/2 data-transmission standard without claiming a scrambler.

The court rejected the defense. The HIPERLAN/2 standard placed a scrambler at the beginning of data transmission, not between the interleaver and mapper. The court found that the standard did not identify scrambling at the location used by the accused technology as an alternative to a claim limitation. Thus, the accused scrambling arrangement was not dedicated to the public.

The court noted that the ’768 patent discussed, rather than incorporated by reference, the HIPERLAN/2 standard, but it did not need to decide whether that distinction independently defeated the defense. The court also used the 2000 version of the standard because the parties could not provide the 1999 version incorporated by the ’230 patent.

Claim Vitiation

Claim vitiation is a defense under which a court rules that the doctrine of equivalents cannot apply if the proposed equivalent would eliminate an entire claim element. The defendants argued that Regents’ theory would eliminate the requirement that the mapper directly map interleaved data.

The court rejected that argument because nothing in the claims or prosecution history required the interleaver and mapper to be directly connected without intervening steps. The court concluded that inserting a scrambler did not eliminate a claim element and therefore did not vitiate the claim.

Disposition

The court held that none of the defendants’ three defenses barred Regents’ doctrine-of-equivalents infringement contentions. Judge John R. Tunheim ordered that the defendants’ motion for summary judgment of non-infringement of U.S. Patent Nos. 7,251,768 and RE45,230 under the doctrine of equivalents is DENIED.

The opinion does not determine whether the defendants ultimately infringed the patents. It resolves only the defendants’ motion asserting that the three defenses required judgment in their favor as a matter of law.