Don’t Forget the Stay: Federal Circuit Addresses Timing Requirement Under 28 U.S.C. § 1659(a)

In Ascendis Pharma A/S v. Biomarin Pharmaceutical Inc., the Federal Circuit addressed the timing requirement for a mandatory stay under Section 1659(a)(2). Ascendis, an ITC respondent who was also the plaintiff in a U.S. district court action, missed the original deadline to seek a mandatory stay and attempted to cure the defect by voluntarily dismissing and refiling the district court action, attempting to restart the statutory 30-day period. Ascendis Pharma A/S v. Biomarin Pharm. Inc., 170 F.4th 1368, 1372–73 (Fed. Cir. 2026).

The relevant procedural schedule in Ascendis is as follows:

• On April 1, 2025, BioMarin Pharmaceutical Inc. (BioMarin) filed a complaint at the ITC alleging that Ascendis Pharma Inc., Ascendis Pharma A/S, and Ascendis Pharma Growth Disorders A/S (collectively, “Ascendis”), among others, infringed U.S. Patent No. RE48,267. Certain Drug Products Containing C-Type Natriuretic Peptide Variants, and Components Thereof, Inv. No. 337-TA-1447 (U.S.I.T.C.), Compl.
• On April 11, 2025, Ascendis filed a declaratory judgment action in the Northern District of California against BioMarin, seeking a finding that it did not infringe U.S. Patent No. RE48,267. Ascendis Pharma A/S et al. v. BioMarin Pharm. Inc., No. 4:25-cv-03302 (N.D. Cal.) (Ascendis I).
• On May 2, 2025, the ITC instituted the investigation. Certain Drug Products Containing C-Type Natriuretic Peptide Variants, and Components Thereof, Inv. No. 337-TA-1447, Notice of Institution, (May 2, 2025).
• On May 16, 2025, BioMarin filed a motion to dismiss. Ascendis I, Dkt. 31.
• On May 30, 2025, Ascendis opposed BioMarin’s motion to dismiss. Ascendis I, Dkt. 33.
• On July 7, 2025, Ascendis filed a notice of voluntary dismissal in Ascendis I, stating that it intended “to re-file a declaratory judgment complaint for non-infringement of U.S. Reissue Patent No. 48,267, which new action it plans to stay pursuant to the mandatory stay provision of 28 U.S.C. § 1659 in favor of parallel ITC proceedings.” Ascendis I, Dkt. 45.
• On July 7, 2025, Ascendis filed a new declaratory judgment action in the Northern District of California against BioMarin, again seeking a finding that it did not infringe U.S. Patent No. RE48,267. Ascendis Pharma A/S et al. v. BioMarin Pharm. Inc., No. 4:25-cv-05696 (N.D. Cal.) (Ascendis II).
• On July 21, 2025, Ascendis moved to stay Ascendis II, citing Section 1659(a)(2). Ascendis II, Dkt. 25 at 3.
• On August 4, 2025, BioMarin opposed the motion by Ascendis to stay as untimely but filed its own motion seeking a discretionary stay under Landis v. North American Co., 299 U.S. 248 (1936). Ascendis Pharma A/S, 170 F.4th at 1373; Ascendis II, Dkts. 35, 36.
• On September 19, 2025, the district court denied the motion by Ascendis to stay but granted BioMarin’s motion to stay. Ascendis Pharma A/S, 170 F.4th at 1373.

On appeal, the Federal Circuit considered, among other issues, whether Ascendis’ motion to stay under Section 1659 was timely. The court held that it was not because Ascendis’ voluntary dismissal of Ascendis I was an improper attempt to circumvent Section 1659’s timing requirement. The court explained that the common-law principle “prohibits the use of voluntary dismissal as an indirect way to avoid the explicit requirements of other rules.” Ascendis,170 F.4th at 1378 (quoting Russ v. Standard Ins. Co., 120 F.3d 988, 990 (9th Cir. 1997)). Applying that principle, the court concluded that Ascendis could not obtain a mandatory stay through voluntary dismissal and refiling after it had missed the statutory deadline.

Ascendis argued on appeal that the district court’s reliance on Russ, which prohibits the use of dismissal to avoid other rules, was misplaced because, unlike the plaintiff in Russ, Ascendis had not refiled its complaint to request a jury trial. Ascendis also sought to distinguish Russ on the ground that the failure to request a jury trial could not be cured under Federal Rule of Civil Procedure 39(b). The Federal Circuit disagreed, holding that the same principle applied to Ascendis’ attempt to avoid a different rule with different deadlines.

The Federal Circuit also rejected Ascendis’ argument that because Section 1659 is not limited to the “initial” pleading—unlike the removal statute, 28 U.S.C. § 1446, which expressly addresses initial and amended pleadings—there was no reason to limit the stay period to the initial pleading. The court found that argument “too speculative.” It explained that, unlike in the removal context, where a party may not discover that a case is removable until after the initial pleading, a party would be unaware of a pending ITC proceeding only if it had not yet been named as a respondent in the ITC proceeding. Thus, the statutory language requiring a party to seek a stay within “30 days after the party is named as a respondent in the proceeding before the Commission” addresses that scenario (emphasis added). 28 U.S.C. § 1659(a)(1). The court further stated that the legislative history supported its view that the 30-day period does not restart with a refiled complaint because that interpretation avoids abuse and encourages prompt adjudication. Ascendis, 170 F.4th at 1379–80.

The opinion underscores the importance of timely moving to stay district court litigation when parallel ITC proceedings support a mandatory stay. As Ascendis illustrates, if a mandatory stay is unavailable, a party may still seek a discretionary stay, but the two forms of relief differ in important respects. For example, a district court may lift a discretionary stay if circumstances change, whereas a mandatory stay remains in place until the ITC proceedings reach a final determination.