Uniloc “Locking” LG & Facebook Out? Not So Fast. CAFC Upholds Board’s “No Estoppel” Finding in Uniloc 2017 LLC v. Facebook Inc.

Joinder may allow a party to challenge patent claims with an IPR even if the one-year time bar in Section 315(b) would otherwise preclude the party from filing a petition for IPR. In Uniloc 2017 LLC v. Facebook Inc., Nos. 19-1688, -1689 (Fed. Cir. 2021), the Federal Circuit resolved whether the joining party can continue the challenge even if the original petitioner no longer can due to estoppel.
Under Section 315(e)(1), when an IPR proceeding results in a final written decision with respect to a patent claim, a petitioner, or the RPI or privy of the petitioner, “may not request or maintain” another IPR that the party “raised or reasonably could have raised” in the prior proceeding. Section 315(e)(1) serves two purposes: it protects the defending party from a second attack on the same claim and ensures that the petitioner can still bring challenges that it has not had a full and fair opportunity to do so.

In Uniloc, after a party joined an ongoing IPR, the original petitioner of that IPR became estopped from continuing its challenge due to its involvement in an earlier IPR challenging claims of the same patent. The question the Federal Circuit faced was whether the joining party was also estopped from continuing the challenge.

On appeal, the Federal Circuit found that moving to join a prior petition alone does not make a party a real party in interest (RPI) or privy of the petitioner. However, the court noted that this is highly fact-dependent. In this case, the Federal Circuit found insufficient evidence that the joining party was a RPI or in privity of the original petitioner. This means that the joining party, merely joining the original petition, was not estopped in challenging the claims.


1. Joinder alone does not burden a party that has joined an IPR with the original petitioner’s estoppel. On the contrary, in an estoppel context, patent owners will need evidence other than joinder to prove a party is a RPI or privy of the petitioner. This may include, for example, evidence of joint funding, of a coordinated IPR effort, or of a sufficiently close relationship such that the party already had a chance to litigate the claim.

2. The decision clarified that when the estoppel-triggering event occurred after institution, PTAB decisions concluding that the estoppel provisions do not apply are reviewable on appeal. Contrast Uniloc with Thryv, Inc. v. Click-to-Call, 140 S. Ct. 1367 (2020) where the Supreme Court ruled that the Federal Circuit may not review PTAB time-bar determinations under Section 315(b) because the one-year time bar is “integral to, indeed a condition on, institution.” Thus, petitioners should avoid relying on the Federal Circuit for judicial review given the limited opportunities for review under Section 314(d).

3. A petitioner is not barred from continuing a challenge to a dependent claim in a second IPR when the same claim was not included in the first IPR. In this case, the Federal Circuit relied on the plain language of Section 315(e)(1) and concluded that the original petitioner was not estopped in challenging the dependent claim because it was not addressed in the final written decision of the first IPR. However, petitioners should still be careful about ongoing IPRs as it may give rise to an estoppel of the petitioners’ separate IPR on the same claims of the patent.