Background

Until 2006, district courts routinely granted permanent injunctions, along with damages, to prevailing patent owners after trial on the grounds that irreparable harm was presumed. The Supreme Court’s decision in eBay v. MercExchange, L.L.C., 547 U.S. 388, 393–94 (2006), represented a sea-change in patent infringement litigation. The decision abolished the presumption of irreparable harm caused by infringement, holding that a patent owner must establish all four parts of the traditional test for permanent injunctive relief: “(1) that it has suffered an irreparable injury; (2) that remedies available at law, such as monetary damages, are inadequate to compensate for that injury; (3) that, considering the balance of hardships between the plaintiff and defendant, a remedy in equity is warranted; and (4) that the public interest would not be disserved by a permanent injunction.” 

No presumption of irreparable harm exists for preliminary injunctions

Although the rationale in eBay regarding permanent injunctions seemingly should apply to preliminary injunctions as well, the Federal Circuit had never squarely so held until August 4, 2026, when the court vacated a grant of a preliminary injunction in Socket Solutions, LLC. v. Import Global, LLC. While it was unclear from the record whether the district court had applied a presumption of irreparable harm to its fact findings in granting the preliminary injunction, the Federal Circuit held that to the extent the district court had applied such a presumption, doing so would have been in error because “this presumption cannot be justified after eBay Inc.”

Chief Judge Moore, writing for the panel, stated plainly that the presumption of irreparable harm was abolished as it applied to determining injunctive relief after eBay. Although eBay and its progeny involved permanent injunctions, “we see no reason to depart from their holdings in the preliminary injunction context.”

A reminder that claim construction is important for preliminary injunctions, too

As discussed above, the Federal Circuit’s express holding regarding applicability of eBay to preliminary injunctions is of primary importance. In addition, in Socket Solutions, the panelconfirmed that claim construction is critical in the context of a preliminary injunction decision. 

As reiterated by the court, to obtain a preliminary injunction, a party must establish that (1) it is likely to succeed on the merits, (2) that it is likely to suffer irreparable harm in the absence of preliminary relief, (3) that the balance of equities tips in its favor, and (4) that an injunction is in the public interest. The first prong – likelihood of success on the merits – requires a showing that the patentee will likely prove infringement. 

Key to that determination is the district court’s construction of any claim terms or phrases necessary for the infringement inquiry. Because the Federal Circuit held that the district court had erred in its claim construction, it reversed and dissolved the preliminary injunction pending further proceedings. In particular, the Federal Circuit held that the district court erred in construing the terms “backplate” and “pin” in its likelihood of success analysis. For “backplate” (illustrated as item 14 in Fig. 3), the Federal Circuit held that the district court’s construction, as well as Import Global’s proposed construction, imposed spatial reference requirements that the specification does not require. The panel instead construed “backplate” as “the component forming the cover with the frontplate, such that the maximum thickness of the cover is the distance, at the central portion of the cover, between the frontplate and the component” and explained that this construction was “most naturally align[ed] with the specification.”

Regarding the claim term “pin” (illustrated as items 18 and 28 in Fig. 5), the Federal Circuit construed it to have its plain and ordinary meaning as understood by a skilled artisan. The panel reasoned that the district court had incorrectly construed the term as a “means-plus-function” term because (1) there is a presumption that 35 U.S.C. § 112(f) does not apply because the term does not use the word “means,” (2) the parties do not dispute “pin” in the context of the patent is understood by skilled artisans as a structure, and (3) there is no definition or disavowal of scope in the specification, or prosecution history to the contrary, requiring departure from the plain and ordinary meaning. The panel also declined to adopt Import Global’s proposed construction of “pin” in purely functional terms as overly broad and unsupported by the specification.

Takeaways

Socket Solutions is noteworthy in two respects. First, to the extent any uncertainty existed, the Federal Circuit put it to rest by expressly holding that eBay’s abolition of the old presumption of irreparable harm in patent infringement cases applies equally to permanent and preliminary injunction proceedings. Second, it highlights the importance of proper claim construction in determining whether a likelihood of success on the merits has been shown by the patentee in support of its motion for a preliminary injunction.