By Dennis Crouch

One risk of claim construction is potential for inconsistent judgments between different district court judges who each are required to construe disputed claim terms. In e.Digital v. Futurwei (Huawei), the district court cut this knot by applying the doctrine of collateral estoppel (issue preclusion) to preclude the patentee from seeking a construction that varied from that of a prior court. On appeal, the Federal Circuit has largely affirmed — however, the appellate panel rejected the notion that collateral estoppel applies to the construction of identical terms found in a second asserted patent since that second-patent was not at issue in the prior case and had material differences. [Read the Court Decision]

Due process generally requires Courts to allow parties a chance to make their case. However, the doctrine of collateral estoppel blocks parties from re-litigating issues that had already been finally decided. Generally, the issue being precluded must have been actually litigated by the party being precluded and necessarily decided as part of a valid final judgment. Because claim construction is an interlocutory decision and subject to modification, preclusion does not kick-in until a final judgment is awarded.

Here, a prior Colorado Court construed the terms of e.Digital’s U.S. Patent Nos. 5,491,774. The ‘774 patent covers a handheld audio recorder/player. All of the asserted claims require “a flash memory module which operates as the sole memory of the received processed sound electrical signals” (sole memory limitation). The patentee argued that this sole-memory-limitation should not rule-out the use of microprocessors that also require RAM to operate. The Colorado district court disagreed and held that the claims excluded any device with RAM. Under the arguably narrow construction it was clear that the accused infringers did not actually infringe and the parties stipulated to a dismissal of the case.

In the present action against Huawei, e.Digital asserted both the ‘774 patent and Patent No. 5,839,108. Although the ‘108 patent is not an official ‘family member’ (e.g., not a continuation, CIP, or divisional), it does cover the same basic device and includes the identical sole memory limitation.

On appeal, the Federal Circuit found that, despite the identical limitation, it was improper for the district court to rely on issue preclusion to bar the patentee from litigating construction of the sole memory limitation term with respect to the ‘108 patent.

The ’108 patent . . . presents a separate claim construction issue. The ’108 patent is not related to the ’774 patent, but does disclose a purported improvement to the ’774 patent. While the ’108 patent may incorporate by reference the ’774 patent as prior art, it does not change the fact that the patents are not related. The ’108 patent discloses a separate invention, includes a distinct prosecution history, and is supported by a different written description—including Figures 3 and 4 which clearly depict RAM. These distinctions reinforce the well understood notion that claims of unrelated patents must be construed separately. Texas Digital Sys., Inc. v. Telegenix, Inc., 308 F.3d 1193, 1211 (Fed. Cir. 2002) (citing Abbott Labs. v. Dey, L.P., 287 F.3d 1097, 1104 (Fed. Cir. 2002)) (explaining that a claim of an unrelated patent “sheds no light on” the claims of the patent in suit). Because the asserted patents are not related, the ’108 patent requires a new claim construction inquiry and the court therefore erred in applying collateral estoppel to the ‘108 patent.

The holding here is partially based upon the fact that the two patents are not formally related according to the rules of priority. However, the court added – in dicta – that issue preclusion might not apply even if they had been related.

To be clear, our decision that collateral estoppel cannot apply to the construction of a claim in one patent based on a previous claim construction of an unrelated patent is not an invitation to assume the opposite is always justified. That is, a court cannot impose collateral estoppel to bar a claim construction dispute solely because the patents are related. Each case requires a determination that each of the requirements for collateral estoppel are met, including that the issue previously decided is
identical to the one sought to be litigated. A continuation-in-part, for instance, may disclose new matter that could materially impact the interpretation of a claim, and therefore require a new claim construction inquiry.

The point here is that issues involving a related but previously un-asserted patent ‘might’ be subject to issue preclusion based upon whether the new patent requires consideration of arguments and facts that are distinct from the already issued patent.

Going forward, this case offers some considerations for patent portfolio management both at the filing/prosecution stages as well as the assertion stage. This case, coupled with other prior Federal Circuit decisions provide value in splitting-up larger patents into smaller component patents and in potentially holding-back some patents from initial rounds of litigation.