The Mandate Rule Has Limits: Federal Circuit Lets the PTAB Revisit Unresolved Issues

In a precedential decision, the Federal Circuit affirmed a Patent Trial and Appeal Board (Board or PTAB) determination following remand and clarified the scope of the mandate rule in proceedings before the Board. The court held that the mandate rule does not preserve every factual observation in an earlier Board decision merely because the Federal Circuit did not expressly disturb it. Rather, the relevant questions are whether the issue was within the scope of the appealed judgment and whether it was actually decided on appeal, expressly or by necessary implication.

BACKGROUND

Intellectual Pixels Limited (IPL) owns US Patent No. 10,681,109, which concerns generating digital images through an external visual server.[1] The patent shifts all visual processing to the server, leaving the client device to collect and transmit user inputs and to decompress and display the images returned by the server.[2]

Sony Interactive Entertainment LLC (Sony) petitioned for inter partes review of claims 1–18.[3] After IPL disclaimed claims 13–18, the dispute proceeded as to claims 1–12.[4] Sony relied principally on US Patent No. 6,409,602 (Wiltshire), which disclosed a server-hosted gaming system that transmitted images, including compressed moving picture experts group (MPEG) video streams, to client terminals and identified Doom among the compatible games.[5]

The Board initially found that Sony had not shown the challenged claims unpatentable, finding that Wiltshire did not disclose generating an updated image at the server.[6] The Federal Circuit vacated that decision in 2023, reasoning that Wiltshire’s disclosed use with Doom necessarily involved generating new images in real time.[7] The court limited its decision to the generating limitation and remanded for further proceedings.[8]

On remand, the Board found that Wiltshire satisfied the generating limitation and that the combination of Wiltshire and US Patent No. 6,404,817 (Saha), which detailed MPEG compression, satisfied the separate compression limitation.[9] The Board therefore held claims 1 and 3–12 obvious over Wiltshire and Saha and held claim 2 obvious over those references together with an additional publication addressing asymmetric data transmission.[10] IPL appealed, arguing that the Board exceeded the Federal Circuit’s mandate by reaching the compression issue.[11]

PTAB MAY RECONSIDER ISSUES OUTSIDE THE SCOPE OF A PRIOR APPEAL

On appeal, IPL principally argued that the Board’s second final written decision exceeded the mandate issued following the Federal Circuit’s October 13, 2023 decision. According to IPL, the Board was required to adhere to factual findings contained in its first final written decision because the Federal Circuit had not expressly set them aside or otherwise disturbed them.[12]

The Federal Circuit clarified that the mandate rule applies to the Board in the same manner that it applies to lower courts.[13] Under that rule, a tribunal on remand may not reconsider an issue that the appellate court previously “actually decided, either explicitly or by necessary implication.”[14] The court explained, however, that the mandate does not foreclose consideration of an issue that did not form the basis of the original judgment, was not properly subject to appeal, and was not decided by the appellate court.[15]

Appellate courts review judgments rather than every observation or subsidiary finding contained in an opinion.[16] Thus, a factual finding in an earlier Board decision is not necessarily binding on remand merely because the appellate court did not expressly disturb it. Instead, the relevant inquiries are whether the issue fell within the scope of the appealed judgment and whether it was actually decided by the appellate court, either explicitly or by necessary implication.[17]

Applying this framework, the Federal Circuit held that the Board did not exceed the scope of the court’s prior mandate by reconsidering whether the previous art disclosed the claimed compression limitation.[18] The Board’s original patentability determination rested solely on its finding that the prior art did not disclose the separate “generating” limitation, and the first appeal addressed only that issue.[19]

Any earlier observations concerning the compression limitation therefore were not part of the appealed judgment, were not properly appealable at that stage, and remained open for consideration on remand.[20]

The court held that its prior decision did constrain the Board’s analysis of the compression issue. The first appeal necessarily rejected the Board’s earlier statement that Wiltshire was silent as to the content or origin of the compressed MPEG stream because the court had already determined that the stream contained a newly generated updated image when Wiltshire’s system was used with Doom.[21] While the compression limitation itself remained open, factual propositions necessarily resolved in the first appeal did not remain open.

PRACTICAL GUIDANCE

This opinion confirms that the mandate rule turns on the scope of the judgment under review, not every finding or observation in the underlying decision. Issues within the scope of the appealed judgment that were decided expressly or by necessary implication are foreclosed on remand; issues that did not form a basis for the judgment and were not decided on appeal generally remain open.

Practitioners therefore should distinguish findings that supported the judgment from comments or subsidiary findings concerning alternative issues that were not reached.

That distinction has implications not only on remand but also during appellate briefing. An appellee generally may present additional arguments in support of the judgment without filing a cross-appeal. In appeals from the Board, however, ordinary limits on judicial review of agency action remain: Where the Board did not decide an alternative issue or make the factual findings necessary to resolve it, the Federal Circuit generally will not decide that issue in the first instance.

If an alternative issue is properly before the court and the court actually decides it, expressly or by necessary implication, that determination ordinarily will constrain the Board on remand. Merely briefing an alternative issue does not bring it within the mandate if the court declines to reach it. Parties therefore should consider not only which issues must be presented to preserve their positions but also whether expressly requesting resolution of an alternative issue could narrow the scope of any subsequent remand.

Once a PTAB matter, including America Invents Act (AIA) trials or ex parte appeals, is remanded, practitioners should identify each ground, claim limitation, and factual issue that the Board did not need to decide in its original decision. In AIA trials, for example, petitioners should be prepared to renew properly preserved arguments, while patent owners should not assume that favorable comments concerning those theories will bind the Board merely because they appeared in the first final written decision.

Even when identifying matters that remain open on remand, practitioners should ensure that factual and legal conclusions necessarily resolved by the appellate court’s reasoning are respected. In this case, the prior appellate decision necessarily resolved that Wiltshire’s disclosed use with Doom involved generating updated images.

The Board therefore could not treat the resulting MPEG stream as wholly silent as to its content or origin, even though the separate compression limitation remained unresolved. Defining the permissible scope of further proceedings requires consideration of both the express holding and the necessary implications of the appellate opinion.