In Thryv, Inc. v. Click-to-Call Technologies, LP, No. 18-916 (April 20, 2020), the Supreme Court held that the U.S. Patent Trial and Appeal Board's decision finding an inter partes review petition to be timely filed was nonappealable.
Under the patent laws, the "determination . . . whether to institute an inter partes review . . . shall be final and nonappealable." 35 U.S.C. § 314(d). In addition, under 35 U.S.C. § 315(b), "[a]n inter partes review may not be instituted if . . . filed more than 1 year after the date on which the petitioner . . . is served with a complaint alleging infringement of the patent." The issue before the Court was whether the one year time limit was nonappealable within the provisions of § 314(d).
The Court found that the Patent Trial and Appeal Board's application of § 315(b)'s time limit was closely related to its decision whether to institute inter partes review, and is therefore also rendered nonappealable by § 314(d).
This decision further restricts the arguments patent owners can make when appealing Patent Trial and Appeal Board decisions.
The decision can be found here: https://www.supremecourt.gov/opinions/19pdf/18-916_f2ah.pdf