Thirty Days to Decide: Parallel ITC Proceedings, the § 271(e)(1) Safe Harbor, and the High Cost of Strategic Miscalculation in Ascendis Pharma A/S v. BioMarin Pharmaceutical Inc.

“Regretting this turn of events, Ascendis hatched a plan to reclaim its statutory right to a § 1659(a)(2) mandatory stay. . . .”

On the morning of April 1, 2025, the day after its competitor, Ascendis Pharma, filed a New Drug Application (“NDA”) with the FDA, BioMarin Pharmaceutical Inc. filed a complaint with the U.S. International Trade Commission (“ITC”). Although pharmaceutical cases are a rarity in the ITC, this drug case was uniquely suited to it. And the complaint’s timing was not coincidental. BioMarin had monitored Ascendis’s development of its “TransCon CNP” drug product and understood well the implications of Ascendis’s NDA filing.

The filing marked the opening countdown of a real competitive threat to the market exclusivity of BioMarin’s “Voxzogo” pharmaceutical, the only FDA-approved treatment for achondroplasia, a rare genetic disorder causing short-limbed dwarfism. BioMarin's ITC complaint was not litigation as a last resort. It was a next move in a multi-forum global enforcement campaign that simultaneously targeted Ascendis in the ITC and the Unified Patent Court in Munich, Germany.

What followed over the next eleven months was a procedural chess match of the kind that will be studied by practitioners advising parties in parallel ITC and district court proceedings well into the future. Each move was inherently complicated by the opaque activities of a third party, the U.S. Food and Drug Administration, which appeared to be moving with unusual speed in its review toward approval of Ascendis’s NDA.

Although the parties continue their fight in the ITC to this day, the drama pertinent here unfolded in parallel district court proceedings brought by Ascendis in the Northern District of California (“NDCA”). Those events are recounted and analyzed in the Federal Circuit's March 26, 2026 precedential decision in Ascendis Pharma A/S v. BioMarin Pharmaceutical Inc., No. 26-1026 (Fed. Cir. Mar. 26, 2026) ("Ascendis, slip op.").

The Federal Circuit’s decision shines a spotlight on Ascendis’s failed efforts to undo what appears to have been a multi-million-dollar strategic error committed in the parallel declaratory judgment case it filed in the NDCA. Ascendis filed the declaratory judgment action to pursue an expedited declaration that all of its pre-FDA approval activities with TransCon CNP were immune from patent infringement liability under the drug development “safe harbor” provided in 35 U.S.C. § 271(e)(1). A long bet seemingly worth taking.

But obtaining that relief required Ascendis to forgo moving for the mandatory stay of the parallel district court action offered by 28 U.S.C. § 1659(a)(2), available only on the condition that Ascendis move for the stay within 30 days of filing its complaint. The mandatory stay would have idled the NDCA until after the ITC issued a final determination. Ascendis wanted the court to act sooner and therefore stood by as the 30-day deadline for the motion passed.

The subject matter of the Federal Circuit’s decision addresses Ascendis’s sudden about-face maneuver to voluntarily dismiss its declaratory judgment action, only to refile a virtually identical case in the same district court the same day. The sole purpose of the dismiss-then-refile scheme was to obtain a § 1659(a)(2) mandatory stay by moving to stay the new case within 30 days of “filing” its complaint.

The Federal Circuit’s headline holding is almost anticlimactic by the time it arrives—an ITC respondent cannot use voluntary dismissal and refiling to restart the thirty-day deadline for requesting a mandatory stay under § 1659(a)(2). Yet, the story worth telling here is how the parties arrived at this unusual juncture—the creative infringement theory BioMarin assembled when the standard Hatch-Waxman toolkit proved unavailable, the strategic miscalculation Ascendis made in the first thirty days of its own lawsuit, and the durable appellate framework the Federal Circuit built before it ever reached the merits.

I. Why BioMarin Chose the ITC

To understand the parties’ procedural maneuvering that produced the Federal Circuit’s ruling, one must first understand why BioMarin brought its patent enforcement action at the ITC rather than—or in addition to—in a district court. The answer lies in the intersection of pharmaceutical patent litigation with its unique procedural framework, the time-to-resolution and specific remedies available in Section 337 proceedings, and a contested question about how far the § 271(e)(1) patent safe harbor for pharmaceutical research and development extends. That context is not provided in the Federal Circuit’s opinion but is explained here.

Most readers familiar with pharmaceutical patent litigation will recognize the standard Hatch-Waxman drama: a pioneer drug manufacturer sues a generic challenger after the challenger files an Abbreviated New Drug Application (“ANDA”) or a so-called “Paper” NDA under Section 505(b)(2) of the Food, Drug, and Cosmetics Act (“FDCA”) and certifies under Paragraph IV of the corresponding FDCA provision that the pioneer’s patent is invalid or not infringed. The filing of the ANDA or Paper NDA with that certification constitutes an “artificial act” of patent infringement under 35 U.S.C. § 271(e)(2), immediately giving the pioneer the right to file suit even though none of the alleged infringing drug product has been sold. If the pioneer files suit within 45 days of receiving formal notice of the challenger’s FDA application, FDA approval of the challenger’s application is automatically stayed for thirty months—a congressionally mandated pause that gives the patent litigation time to reach conclusion before the generic can enter the market.

That framework was simply unavailable to BioMarin here and understanding why is essential to understanding everything that followed. Ascendis’s TransCon CNP is not a generic copy of BioMarin’s Voxzogo. It is a molecularly distinct “C-type natriuretic peptide (CNP)” variant—a novel therapeutic compound developed through Ascendis’s own independent research program. Ascendis therefore was required to file a standard “new drug application (NDA)” for a new molecular entity, not an ANDA or Paper NDA seeking approval based on bioequivalence to an existing approved drug product. Without an ANDA or Paper NDA, there was no § 271(e)(2) artificial act of infringement, no notice of Paragraph IV certification to trigger suit, and critically no automatic thirty-month stay of FDA approval. BioMarin therefore had no opportunity to set the standard Hatch-Waxman litigation machinery into motion.

The consequences of that idle machinery were significant and immediate. Without a thirty-month stay, BioMarin faced the prospect of FDA approving TransCon CNP while any patent infringement litigation was still pending in its earliest stages—potentially enabling Ascendis to launch “at-risk” into the U.S. market before any court had finally adjudicated the patent dispute. In a two-player rare disease market worth hundreds of millions of dollars annually, the impact of an at-risk launch could be commercially irreversible. Speed, for BioMarin, was not merely a luxury. It was a strategic imperative.

But BioMarin faced an even more fundamental threshold obstacle to filing suit against Ascendis—all of Ascendis’s pre-approval activities involving TransCon CNP were presumptively immune from patent infringement liability. Prior to approval, there had been no commercial sale of TransCon CNP in the United States—Ascendis could not legally sell the drug without FDA authorization. And all of Ascendis’s pre-approval development activities with the drug were presumptively shielded by the § 271(e)(1) “safe harbor,” which protects acts “solely for uses reasonably related to the development and submission of information under a Federal law which regulates the manufacture, use, or sale of drugs.”

BioMarin needed a theory of infringement tied neither to commercial sale nor protected by the safe harbor. It potentially found one. As it turned out, Ascendis imported its TransCon CNP into the United States, and the act of importing an infringing article into the United States is an expressly defined act of patent infringement under 35 U.S.C. § 271(a).

BioMarin could be reasonably assured that Ascendis would not dispute its importation of TransCon CNP. Instead, the real battle would, and could only, be waged against specific imports that demonstrably arrived in the U.S. outside the safe harbor. The threshold dispute, therefore, would involve defining the scope and boundaries of the safe harbor.

The § 271(e)(1) safe harbor provides an important immunity from patent infringement liability to pharmaceutical developers. Under that section, it is not an act of infringement to make, use, offer to sell, or import a patented invention “solely for uses reasonably related to the development and submission of information under a Federal law which regulates the manufacture, use, or sale of drugs.” The provision was enacted as part of the Drug Price Competition and Patent Term Restoration Act of 1984—the so-called “Hatch-Waxman Act” in honor of its congressional sponsors—to eliminate patent-based barriers to pre-approval pharmaceutical development. Its scope, as interpreted by the Federal Circuit and the Supreme Court, is broad. The Supreme Court held in Merck KGaA v. Integra Lifesciences I, Ltd., 545 U.S. 193, 202 (2005) that the safe harbor “extends to all uses of patented inventions that are reasonably related to the development and submission of any information under the FDCA.”

Broad as that principle sounds, it has limits. And the Federal Circuit’s 2019 decision in Amgen Inc. v. Hospira, Inc., 944 F.3d 1327 (Fed. Cir. 2019) defined one of the most important of them. In Amgen v. Hospira, Amgen held several patents covering its erythropoietin biologic product. Emboldened by the § 271(e)(1) safe harbor, competitor Hospira manufactured twenty-one batches of biosimilar erythropoietin in the years before its FDA biologics license application (“BLA”) was approved, arguing that the manufacture of all twenty-one batches were protected by the safe harbor because data from each was ultimately submitted to the FDA.

The Federal Circuit affirmed a jury finding that the manufacture of only seven of the twenty-one batches was protected by the safe harbor—specifically the two used to qualify Hospira’s manufacturing process and equipment, and the five manufactured for a mandatory FDA pre-approval inspection. The remaining fourteen failed the safe harbor analysis because, evaluating each accused activity separately, the jury found those fourteen batches were not required for FDA approval.

Although the fourteen batches indisputably were subject to FDA-mandated quality assurance testing, neither the batches’ manufacture nor their testing were necessarily responsive to the FDA’s approval of Hospira’s BLA. Even post-approval batches require routine quality assurance testing subject to FDA scrutiny, and the fourteen pre-approval batches’ commensurate quality assurance testing did little to prove their relevance to the FDA’s review and approval of Hospira’s BLA. In short, the purpose of the fourteen batches appeared grounded more in Hospira’s commercial aspirations and less in its BLA’s approval. The Federal Circuit affirmed the jury’s verdict, making clear that the safe harbor does not extend to pre-approval stockpiling in anticipation of commercial launch, even if the stockpiled product generates FDA-mandated testing data. The jury’s $70 million verdict stood.

Amgen v. Hospira sits as a guidepost in setting the metes and bounds of the safe harbor. BioMarin undoubtedly read it carefully. BioMarin’s complaint alleged not simply that Ascendis was importing TransCon CNP but that the magnitude of the imported TransCon CNP “exceeds any quantity that would be solely for uses reasonably related to the development and submission of information to the FDA.” Ascendis, slip op. at 3. That allegation tracks the Amgen v. Hospira analytical framework precisely and, if proven, it would deprive Ascendis of any categorical defense that the safe harbor extends to all of its imports.

With a potentially viable theory of patent infringement in hand, BioMarin’s next decision focused on the selection of a strategically favorable forum for the dispute. The assertion of infringing imports under § 271(a) could be brought in any properly venued U.S. district court that could assert jurisdiction over Ascendis. As Ascendis’s subsequently filed declaratory judgment action in the NDCA shows, the NDCA was one such forum. And the NDCA is no stranger to complex pharmaceutical patent disputes. The one thing the NDCA lacked, however, was certainty of speed to final adjudication. As it turns out, there is one forum where speed is its hallmark and importation is its specialty—the International Trade Commission.

The Commission operates under a statutory mandate to complete Section 337 investigations of infringing imports within sixteen to eighteen months. An ITC investigation that concluded within eighteen months of institution would partially compensate BioMarin for the loss of the Hatch-Waxman thirty-month stay. And the ITC’s import exclusion order remedy—a directive to U.S. Customs and Border Protection to block importation of infringing articles at the border—was potentially more immediate and potent than any injunctive relief BioMarin might obtain from a district court.

District court injunctions require separate balancing of public and private equities pursuant to eBay Inc. v. MercExchange, L.L.C., 547 U.S. 388 (2006) and have become genuinely uncertain in patent cases. With the rare exception of a discretionary exemption requiring Presidential review, an ITC exclusion order takes effect at the border almost immediately upon the Commission’s final determination of patent infringement. For BioMarin, an ITC exclusion order against TransCon CNP therefore offered a pragmatic result that a district court injunction, or even money damages, could not reliably replicate.

The ITC was also institutionally better suited to the character of BioMarin’s patent infringement theory. The Commission’s core jurisdiction is over unfair importation practices, including importation of infringing goods. A complainant asserting that a foreign drug manufacturer’s import volumes reflect commercial pre-positioning rather than purely permissible regulatory activities is making precisely the kind of claim the ITC was designed to adjudicate. And the ITC’s investigative procedures include both robust overseas discovery mechanisms and established cooperation frameworks with foreign customs authorities. Moreover, the Federal Circuit has already confirmed the ITC’s authority to adjudicate § 271(e)(1) safe harbor disputes. See Amgen, Inc. v. International Trade Commission, 565 F.3d 846 (Fed. Cir. 2009) (safe harbor applies in Section 337 proceedings).

Against this backdrop, BioMarin filed a complaint with the ITC on April 1, 2025, seeking exclusion of Ascendis’s non-exempt imports—one day after Ascendis filed its NDA with the FDA, seeking approval of its TransCon CNP pharmaceutical product. The ITC complaint alleged Ascendis’s infringement of BioMarin’s U.S. Patent No. RE48,267 to the extent Ascendis imported TransCon CNP in amounts exceeding the § 271(e)(1) safe harbor. Ascendis responded to the complaint by asserting that “TransCon CNP has not been approved by the FDA and that it ‘has not made, used, offered to sell, sold, or imported its TransCon CNP into the United States, other than for reasons directly related to obtaining FDA approval.’” Ascendis, slip op. at 3-4.

II. Why Ascendis Filed the Declaratory Judgment Action, and Why It Then Hurried to Dismiss It

On April 11, 2025, ten days after BioMarin filed its complaint in the ITC, Ascendis filed a complaint for declaratory judgment of non-infringement in the Northern District of California. The complaint mirrored Ascendis’s defense in the ITC case, asserting that its manufacture, use, and importation of TransCon CNP was “exempt from patent infringement liability by the statutory safe harbor” of 35 U.S.C. § 271(e)(1). Ascendis Pharma A/S v. BioMarin Pharm. Inc., No. 4:25-cv-03302, Dkt. 1 (N.D. Cal. Apr. 11, 2025).

The declaratory judgment action served several purposes simultaneously. It allowed Ascendis to litigate its safe harbor defense in a district court forum with developed § 271(e)(1) precedent rather than at the ITC, where the safe harbor’s application to the quantity and character of specific pharmaceutical imports was limited to a few prior investigations. And it offered the chance of an expedited summary judgment on the safe harbor question that could influence or moot the ITC proceedings.

After filing its declaratory judgment action, Ascendis was faced with a critical strategic decision that Ascendis alone was statutorily empowered to make. It could pursue its declaratory judgment action in parallel with the ITC investigation, or it could move for a mandatory stay of the declaratory judgment action under 28 U.S.C. § 1659(a)(2) until after the ITC issued a final determination. The time to make that decision was short. Under § 1659(a)(2), Ascendis had to move for the stay within thirty days of filing its declaratory judgment complaint.

Section 1659(a) is worth examining carefully, because its architecture is what Ascendis’s appeal to the Federal Circuit was ultimately all about. Section 1659(a) has two subparagraphs. The first, § 1659(a)(1), concerns a companion district court action filed by the ITC complainant. The second, § 1659(a)(2), contemplates a declaratory judgment action filed by the ITC respondent. In each scenario, the statute empowers only the ITC respondent, here Ascendis, to move for a mandatory stay of the district court action but only if the motion is made within a specified time window. That window is the later of: (1) thirty days after the party is named as a respondent in the ITC proceeding, or (2) thirty days after the district court action is filed. 28 U.S.C. §§ 1659(a)(1), (a)(2).

The thirty-day clock relevant to this case ran from the filing of Ascendis’s declaratory judgment complaint on April 11, 2025 in the NDCA. Ascendis ultimately made the strategic choice to let that deadline pass in favor of pursuing expedited parallel relief in federal district court. It was, in retrospect, a regrettable choice. Over thirty days after filing its declaratory judgment complaint, on May 29, 2025, Ascendis pursued its parallel litigation strategy by moving for expedited resolution of its safe harbor defense.

BioMarin responded to Ascendis’s safe harbor motion by moving in the alternative for either (a) dismissal of the declaratory judgment action or (b) a discretionary stay pending the ITC’s final determination. BioMarin’s motion presented Ascendis with a moment of clarity to reassess its strategy.

First, it was clear to Ascendis that the district court was likely to follow the path of least resistance in ruling on the parties’ motions. The first two options presented to the court involved immediate investment of resources: (1) entertaining Ascendis’s expedited safe harbor motion or (2) ruling on BioMarin’s motion to dismiss. The third option invited by BioMarin’s alternative motion would allow the court to stay the case, perhaps indefinitely. Under such circumstances, most courts would be inclined to follow the spirit of § 1659(a) and enter at least a discretionary stay.

Second, it was clear to Ascendis that a discretionary stay would utterly frustrate its ability to seek quick alternative declaratory relief in the district court. At the same time, a discretionary stay would leave an open door to BioMarin to later hijack Ascendis’s own declaratory judgment action against Ascendis itself. In its motion for a discretionary stay, BioMarin had asserted the benefits of the district court “retain[ing] the authority to consider whether the stay should be lifted in the future based on changed circumstances.” Ascendis, slip op. at 7. BioMarin had a specific “changed circumstance” in mind—the fast-approaching FDA approval of Ascendis’s TransCon CNP NDA. Id. BioMarin’s future concerns were not unfounded. The FDA ultimately granted Ascendis’s NDA priority review and signaled its intention to approve the NDA by late 2025 or early 2026—while the ITC investigation was still pending. Id.

This meant that upon FDA’s approval of the NDA, BioMarin could run to district court with a motion to lift the stay and seek a preliminary injunction to preclude Ascendis’s at-risk launch of TransCon CNP before the ITC entered its final determination. The situation would have been quite different had Ascendis moved for a mandatory stay within the thirty-day window of § 1659(a)(2). That mandatory stay would have effectively tied the district court’s hands until after the ITC entered its final determination and conceivably well after Ascendis launched its newly approved product—a timing disparity potentially worth hundreds of millions of dollars in this two-player rare disease market.

Regretting this turn of events, Ascendis hatched a plan to reclaim its statutory right to a § 1659(a)(2) mandatory stay. The plan was as bold as it was simple. Because BioMarin had not yet answered the declaratory judgment complaint, Ascendis could voluntarily dismiss the complaint with neither court order nor opposing party consent under Federal Rule of Civil Procedure 41(a)(1)(A)(i). Ascendis could then file a new declaratory judgment action and immediately move for a mandatory stay.

True to the plan, two weeks after BioMarin filed its motion to dismiss or alternatively stay Ascendis’s declaratory judgment case, Ascendis voluntarily dismissed its complaint. The notice of voluntary dismissal included language that would later haunt Ascendis during its appeal to the Federal Circuit. In the notice, Ascendis candidly explained its intention to “fil[e] a new action rather than amending the complaint and moving to stay the instant action in order to avoid any possible dispute about the applicability to the present action (which has been pending for more than 30 days) of the mandatory stay provided by [§ 1659(a)(2)].” Ascendis, slip op. at 4 (emphases added). That same day, Ascendis filed a virtually identical complaint in the same court and, two weeks later, moved for a mandatory stay.

BioMarin opposed the mandatory stay motion as untimely. It argued that Ascendis had already missed the § 1659(a)(2) deadline when it allowed thirty days to pass after filing the original complaint without requesting a stay and that the voluntary dismissal and refiling could not revive a clock that had already expired. BioMarin separately renewed its motion for a discretionary stay. On September 19, 2025, the district court granted BioMarin’s requested discretionary stay and denied Ascendis’s motion for a mandatory stay as moot. Ascendis, slip op. at 4-5.

That ruling laid peculiar groundwork for Ascendis’s appeal to the Federal Circuit. To the casual observer, the appeal of an expressly non-final procedural ruling would appear “dead on arrival” at the appellate court. Not surprisingly, most of the Federal Circuit’s analysis was devoted to checking the appeal’s jurisdictional vital signs before reaching the merits of the presented § 1659(a)(2) issues.

III. What the Federal Circuit Did—and What Will Endure

 

A. Standing: Events Overtake the Arguments

The first obstacle Ascendis confronted was demonstrating that it had Article III standing to appeal the denied mandatory stay at all. Standing requires showing (1) a concrete injury in fact (2) that is fairly traceable to the challenged conduct and (3) that is likely to be redressed by a favorable decision. Ascendis, slip op. at 6. In September 2025, when the district court entered its stay order, the injury Ascendis asserted was still largely prospective. FDA had not yet approved TransCon CNP. BioMarin had threatened to move for a preliminary injunction but had no factual basis to do so. And as BioMarin emphasized, there was no guaranty the district court would even entertain lifting the stay if those contingencies ever materialized.

Surprisingly, events unfolding during the appeal substantially resolved the speculation surrounding the standing issues. After briefing was finished, Ascendis filed a series of Appellate Rule 28(j) letters, updating the court on the status of its NDA approval. The letters disclosed in real time that FDA granted priority review; the original November 30, 2025 approval target date was postponed to February 28, 2026; and finally, on February 27, 2026, shortly following oral argument, the FDA approved TransCon CNP. The Federal Circuit was further informed that within days of the FDA’s approval, BioMarin informed Ascendis of its intention to move for a preliminary injunction with briefing scheduled for completion before the April 2026 ITC trial date. The speculative contingencies BioMarin relied upon in its appellate briefing to defeat standing had all come to pass.

As interesting as that unfolding drama might be, the Federal Circuit trained its focus upon the district court’s stay ruling itself, noting that had the district court granted a mandatory rather than a discretionary stay, BioMarin’s ability to advocate for lifting the stay would never have been an option at all. Ascendis, slip op. at 8. It was the district court’s entry of a discretionary stay that preserved the precise power BioMarin said it planned to exercise against Ascendis, thereby creating an injury in fact. And it was BioMarin’s own repeated emphasis on the importance of the court “retain[ing] the authority to consider whether the stay should be lifted in the future based on changed circumstances” that proved the threat was not speculative. Id. at 7. “Based on these circumstances,” the Federal Circuit held, “Ascendis has demonstrated a controversy of sufficient immediacy and reality to satisfy Article III standing.” Id. at 8.

 

B. Collateral Order Jurisdiction: The Decision’s Most Durable Holding

Article III standing was necessary but not sufficient. The Federal Circuit’s appellate jurisdiction is ordinarily limited to final decisions of the district court, and the order denying Ascendis’s mandatory stay request was unambiguously interlocutory. To reach the merits, the court had to satisfy itself that the denial qualified for immediate review under the collateral order doctrine—a narrow exception permitting interlocutory appeal where an order (1) conclusively determines the disputed question, (2) resolves an important issue completely separate from the merits, and (3) is effectively unreviewable on appeal from a final judgment. Ascendis, slip op. at 9 (citing DePuy Synthes Prods., Inc. v. Veterinary Orthopedic Implants, Inc., 990 F.3d 1364, 1368 (Fed. Cir. 2021)).

The first two prongs presented little difficulty. The district court’s statement that Ascendis had actually met the statutory requirements for a mandatory stay under § 1659(a)(2) in its second-filed suit, followed immediately by its denial of that stay as moot, constituted a conclusive determination of the disputed question on a fully developed record. And the mandatory stay question was plainly separate from the underlying merits of Ascendis’s request for a declaration that it does not infringe BioMarin’s patent.

The third prong—effective unreviewability after final judgment—is where the Federal Circuit did its most durable analytical work, and it is the analysis that practitioners even outside the pharmaceutical patent world will study and cite in future briefing. The court reached back to its own 2007 decision in In re Princo Corp., 478 F.3d 1345 (Fed. Cir. 2007), where Princo had sought a writ of mandamus to compel a § 1659(a)(2) stay after Philips filed simultaneously at the ITC and in district court. In the mandamus context, the Princo court had reasoned that the § 1659 right “cannot be vindicated by direct appeal from the ultimate damages determination since § 1659 is designed to prevent the ongoing damages proceedings from occurring at all.” Id. at 1357. The insight translates directly to the collateral order context. The harm of dual-track litigation is its occurrence. Once the litigation has proceeded, no appellate ruling can un-litigate it. The clock cannot be turned back.

The Federal Circuit reinforced this conclusion with reference to two analogous holdings from other circuits—the First Circuit’s analysis of an automatic bankruptcy stay in Municipality of San Juan v. Puerto Rico, 919 F.3d 565 (1st Cir. 2019) (“protection from litigation under the automatic stay is effectively unreviewable on appeal from a final judgment”) and the Third Circuit’s treatment of a statutory stay denial in Praxis Properties, Inc. v. Colonial Savings Bank, 947 F.2d 49 (3d Cir. 1991) (denial of statutory stay “effectively unreviewable on appeal from a final judgment”). Both courts concluded that the denial of a statutory right to avoid litigation cannot be made whole after the litigation has run its course.

In doing so, the Federal Circuit joined this analogous precedent with a consonant jurisdictional framework: any denial of a § 1659(a) mandatory stay is immediately appealable, in this case and in every future case. ITC respondents denied a mandatory stay now have a confirmed, direct path to emergency appellate review—a meaningful procedural guarantee that did not exist in such clear terms before Ascendis.

 

C. The “Harmless” Mootness Error

Before reaching the § 1659(a)(2) merits, the Federal Circuit addressed a threshold point that warrants more attention than it received in the decision itself. The district court denied Ascendis’s motion for a mandatory stay as “moot” after granting BioMarin’s motion for a discretionary stay in the second-filed declaratory judgment action.

The Federal Circuit dispelled that notion quickly, ruling in unequivocal terms: “a discretionary stay that can be lifted should circumstances change is not the same as—and thus does not moot—a request for a mandatory stay that cannot be lifted until a final decision in the ITC proceedings.” Ascendis, slip op. at 12. Treating the lesser relief as mooting the greater therefore erroneously collapses two fundamentally different forms of protection into one.

The Federal Circuit went on to hold that although the district court rendered its “mootness” determination in error, “[t]he district court’s error in this regard was nonetheless harmless.” Id. That framing of the error as “harmless” was procedurally significant, especially in view of the Federal Circuit’s ultimate affirmance of the district court’s decision. Indeed, the harmless error determination concerned less the substance of the error and more the posture of the record before the court, the intended outcome of the appeal, and judicial pragmatism.

First, the Federal Circuit made clear that it was not confronted with an undeveloped appellate record. Although the district court concluded that Ascendis’s § 1659(a)(2) motion was “moot,” it did so while expressly stating, without analysis, that “Ascendis had met the statutory requirements for a stay under § 1659(a)(2)” in the second-filed action. Id. at 10. Seizing upon the district court’s legal conclusion, the Federal Circuit treated the issue as having been “conclusively determined” by the district court, emphasizing that in the Federal Circuit’s view, “the record was fully developed for purposes of determining whether Ascendis was entitled to a mandatory stay.” Id.

Second, because the § 1659 issue turned entirely on a legal question—whether Ascendis could restart the 30-day clock through voluntary dismissal and refiling—no further factual development was necessary. With a complete factual record and a purely legal issue before it, the Federal Circuit examined the contours of the statutory interpretation issue itself, ultimately holding that Ascendis was not entitled to a mandatory stay in the second-filed declaratory judgment action.

Characterizing the record below in this manner reflects a pragmatic appellate choice that avoided a costly and unnecessary remand. And the Federal Circuit’s “harmless error” finding permitted the Federal Circuit to affirm the district court’s bottom-line denial of the § 1659(a)(2) mandatory stay, if not its erroneous legal conclusion. In other words, the district court had orchestrated the correct outcome in the case, denial of the mandatory stay, but for the wrong reasons. The Federal Circuit was thus able to affirm the decision below and then return the parties to the district court with the discretionary stay left undisturbed.

 

D. The § 1659(a)(2) Merits: The Statute Reads What the Record Confirms

By the time the Federal Circuit reached the § 1659(a)(2) merits, the outcome was largely determined—not because the statutory question lacked difficulty, but because Ascendis had effectively supplied the answer in its own filings. In its Rule 41 dismissal of the first declaratory judgment action, Ascendis left no room for ambiguity: “Ascendis is filing a new action rather than amending the complaint . . . in order to avoid any possible dispute about the applicability to the present [first] action (which has been pending for more than 30 days) of the mandatory stay. . . .” Ascendis, slip op. at 14. It was clear to all that Ascendis had used procedural maneuvering to recapture a lost opportunity.

The Federal Circuit began its analysis of § 1659(a)(2) by looking to “the backdrop of the common law” for analogous rulings in similar circumstances. Id. at 12–13. In doing so, the court relied on three decisions from other circuits—Russ v. Standard Insurance Co., 120 F.3d 988, 990 (9^th Cir. 1997) (missed jury demand); Walton v. Eaton Corp., 563 F.2d 66, 71 (3d Cir. 1977) (filing of duplicative complaints); and Cook v. Rocky Mountain Bank Note Co., 974 F.2d 147, 148 (10^th Cir. 1992) (Rule 54(b) finality).

Each of those decisions rejected attempts to use dismissal and refiling to evade procedural limitations. Although the context of each case differed, the common law principle shared among them “prohibits the use of voluntary dismissal as an indirect way to avoid the explicit requirements of other rules.” Russ, 120 F.3d at 990. The Federal Circuit was satisfied that the issues presented in Ascendis’s appeal “fit squarely within the common-law principle of prohibiting the use of voluntary dismissal to accomplish indirectly what cannot be accomplished directly.” Ascendis, slip op. at 14.

In attempting to distinguish these cases, Ascendis clarified an ambiguity surrounding its failure to comply with the statute’s 30-day deadline—Ascendis did not mistakenly miss the deadline but instead intentionally let it pass. According to Ascendis, this fact provided a key distinction because the plaintiffs in the Russ line of cases had each mistakenly missed the relevant deadlines, and the courts were loath to reward their inadvertence. By contrast, Ascendis made a “strategic decision to not request a mandatory stay within 30 days.” Id. The Federal Circuit was less than sympathetic with the argument, commenting only that “[t]his distinction does not make Ascendis’s position more compelling.” Id.

Ascendis further attempted a textual argument, asserting that Congress intentionally used “filed” in the § 1659(a)(2) rather than “initially filed” to liberally tie the clock to any “filed” action. As evidence of Congress’s specificity, Ascendis pointed to the federal case removal statute, 28 U.S.C. § 1446(b), and its express care in distinguishing between “initial” and “amended” pleadings. The Federal Circuit was not convinced. The removal statute acknowledges that a party might not “ascertain” the bases for removal from the “initial” pleading and thus specified subsequent deadlines keyed to events from which removability “may first be ascertained.” Ascendis, slip op. at 15. The only requirement for a mandatory stay under § 1659(a)(2) is that the movant for the stay is also a “respondent” in a co-pending ITC investigation. The uncertainties attendant to each statute are not of the same degree. The Federal Circuit therefore found Ascendis’s asserted inferences about congressional intent “too speculative” to overcome the ordinary meaning of § 1659(a)(2). Id.

In conclusion, the Federal Circuit looked to the statute’s legislative history to confirm the 30-day deadline was designed “to avoid abuse” and “encourage prompt adjudication.” Id. (quoting H.R. Rep. No. 103-826(I), at 141–42). The court was satisfied that Ascendis’s dismiss-and-refile maneuvering to recapture the mandatory stay serves neither end.

One boundary not addressed by the decision is worth noting. The court’s analysis repeatedly emphasized the “virtually identical” nature of the original and refiled complaints. Ascendis, slip op. at 13. That limitation portends a harder case where the second action is not merely a procedural duplication but a substantively distinct pleading that adds newly accused products or claims not previously available when the original complaint was filed. Where that line will be drawn remains to be seen. For now, Ascendis establishes the logical baseline. When refiling replicates rather than transforms the original action, the statutory 30-day clock runs from the first filing, and the clock cannot be reset.

 

IV. What Ascendis Leaves Behind

Ascendis will largely be cited for the proposition that a voluntary dismissal cannot restart the thirty-day clock under § 1659(a)(2). It should also be read for something larger. BioMarin's enforcement campaign was a lesson in improvisation under constraint. Its lawyers assembled a coherent litigation strategy from pieces the standard Hatch-Waxman framework did not provide, directed it at a forum purpose-built for the theory at hand, and drove it at a speed the absence of a thirty-month stay made necessary.

That model is potentially available to any U.S. patent holder facing an overseas NDA filer in a narrow therapeutic category, and the ITC's combination of speed, exclusion order remedy, and contested § 271(e)(1) terrain makes it a formidable one. Foreign pharmaceutical companies who import novel compounds into the U.S. market should understand the template as well as the constraints imposed by Amgen v. Hospira on the patent safe harbor.

What the Ascendis litigation also reveals—and what neither side's lawyers may have fully appreciated at the outset—is that § 1659 presents both the ITC complainant and the ITC respondent with a consequential wild card: whether to file a parallel district court action at all, and on what terms. BioMarin, for its part, conspicuously declined to file its own parallel district court infringement action.

The likely reason is instructive. Had BioMarin done so, Ascendis could have invoked § 1659(a)(1) and obtained a mandatory stay of that action, rendering it inert for precisely the period BioMarin needed it most. BioMarin instead placed its full confidence in the ITC's own arsenal. That arsenal was not trivial. The Commission can issue a temporary exclusion order to block further infringing imports while the investigation is pending. It can issue a temporary cease-and-desist order to prevent the use or sale of already-imported product after FDA approval—directly targeting any commercial inventory that might arrive outside the safe harbor's protection. Neither remedy requires a separate equitable showing. Both operate within the ITC's jurisdiction without exposing BioMarin to the mandatory stay trap. BioMarin's decision to stay out of district court was, in hindsight, the strategically correct one.

Ascendis faced the mirror image of that calculation and chose differently. By filing its declaratory judgment action, Ascendis believed it was seizing the initiative by gaining access to a favorable forum, developed precedent, and the possibility of expedited relief. What it actually accomplished was handing over to BioMarin the most potent tool available to stop an at-risk launch: a live but temporarily stayed district court proceeding that, once FDA approval arrived, could be activated for a preliminary injunction with a single motion to lift the stay.

The § 1659(a)(2) mandatory stay, had Ascendis invoked it within thirty days, would have neutralized that threat entirely, locking the district court proceeding away until after the ITC concluded. Instead, Ascendis let the window close, then tried to reopen it, and the Federal Circuit said no. The lesson for any pharma ITC respondent contemplating a parallel district court filing is the same one Ascendis learned the hard way: the decision to file is also the decision to choose, immediately and irrevocably, between two fundamentally different litigation postures.

There are no do-overs.