The Federal Circuit recently affirmed a Patent Trial and Appeal Board decision finding claims that had been subject to an ex parte reexamination unpatentable. As a threshold issue, the court held that IPR estoppel under 35 USC § 315(e)(1) does not apply to ongoing ex parte reexaminations. Accordingly, the Patent Office did not err in continuing the reexamination after issuing final written decisions in co-pending IPRs.