Ascendis Pharma A/S v. BioMarin Pharmaceutical Inc., Appeal No. 2026-1026 (Fed. Cir. Mar. 26, 2026)

The Federal Circuit’s only precedential opinion last week was not quite a “patent case,” but instead concerned when a stay of district court proceedings is available to a respondent in a Section 337 proceeding before the U.S. International Trade Commission.  While 28 U.S.C. § 1659(a) provides that such a stay is mandatory if requested within 30 days of the respondent being named in the ITC action or of the district court action being filed (whichever is later), the Court held that appellant Ascendis was not permitted to game the deadline by voluntarily dismissing its own declaratory judgment action without prejudice and then re-filing it.  En route to that determination, the reviewing panel also upheld Ascendis’s standing to appeal an interlocutory order entering a discretionary stay, as opposed to the mandatory stay Ascendis had sought under the statute.

The underlying dispute concerned pediatric treatments for achondroplasia (a form of genetic dwarfism) using C-type natriuretic peptide (CNP) variants.  Appellant Ascendis sought FDA approval for a new CNP treatment, and BioMarin filed an ITC complaint seeking to  enjoin Ascendis’s importation of the drug on grounds that it infringed BioMarin’s patent.  Ascendis contended that it was exempt from infringement liability under the safe-harbor provisions of 35 U.S.C. 271(e)(1)—which immunizes otherwise infringing acts undertaken solely for regulatory approval purposes—and filed a district court action seeking declaratory judgment to that effect.  When it became apparent FDA approval for the new drug would soon be granted, however, and that BioMarin would seek preliminary injunctive relief when it was, Ascendis reversed course and sought to stay the district court litigation pending completion of the ITC proceedings.

Because more than 30 days had passed since Ascendis was named in the Section 337 proceedings and since it had filed its lawsuit, Ascendis dismissed its case without prejudice and then re-filed a substantially similar declaratory judgment complaint, expressly stating that this was “to avoid any possible dispute” about the availability of a mandatory stay under § 1659.  BioMarin opposed the mandatory stay request as untimely, and instead sought a discretionary stay of the district court proceedings that could be lifted “based on changed circumstances,” e.g. Ascendis commencing sales of its new drug upon FDA approval, which BioMarin would seek to enjoin.  The district court entered BioMarin’s discretionary stay and denied Ascendis’s request for a mandatory stay as “moot.”

Ascendis appealed, and the Federal Circuit first considered whether it had appellate jurisdiction.  The Court determined that it did, reasoning that while a mandatory stay would necessarily have remained in place until the ITC proceedings were completed, the discretionary stay raised the possibility of Ascendis being subjected to preliminary injunction proceedings before that happened.  On the facts presented—including evidence that FDA approval was in fact imminent, and BioMarin’s repeated express statements that it would seek injunctive relief—the Court found that this prospective harm was sufficiently immediate to confer Article III standing on Ascendis to appeal.  The Court also found the interlocutory order reviewable under the collateral order doctrine, since (inter alia) the purpose of § 1659(a) was to protect Section 337 respondents from dual-track litigation under appropriate circumstances, and denial of the mandatory stay would be effectively unreviewable after a final determination of the district court action on the merits.

Having agreed with Ascendis that it had jurisdiction, the Court also agreed that the district court erred by denying the mandatory stay request as “moot,” since as discussed above, there were material differences between the discretionary stay the court entered and the mandatory stay it denied.  However, the Court found this error to be harmless, since it ultimately agreed with BioMarin that Ascendis was not entitled to a mandatory stay under § 1659(a).  Specifically, the Court applied a common-law principle that “prohibits the use of voluntary dismissal as an indirect way to avoid the explicit requirements of other rules,” and held that Ascendis was not permitted to skirt the statute’s 30-day deadline by dismissing and then re-filing its declaratory judgment action.  The Court also found this result to be consistent with § 1659(a)’s legislative history, which indicated the purpose of the deadline was “[t]o avoid abuse of [the stay] provision and to encourage prompt adjuciation in the district courts.”  Finding that “allow[ing] Ascendis to re-file its complaint to get around the 30-day deadline does not ‘avoid abuse’ or ‘encourage prompt adjudication,’” the Federal Circuit affirmed the district court’s decision.

The opinion can be found here.

By Jason A. Wrubleski

This article summarizes aspects of the law and does not constitute legal advice. For legal advice with regard to your situation, you should contact an attorney.