eBay factors (USA)

The four factors to be taken into account in deciding whether to grant an injunction in patent cases, approved by the US Supreme Court in eBay v. MercExchange 547 U.S. 388 (2006) which decided that there was no reason to depart in the patent field from the traditional test applied by courts of equity:

According to well-established principles of equity, a plaintiff seeking a permanent injunction must satisfy a four-factor test before a court may grant such relief. A plaintiff must demonstrate: (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. See, e.g., Weinberger v. Romero-Barcelo, 456 U. S. 305, 311–313 (1982); Amoco Production Co. v. Gambell, 480 U. S. 531, 542 (1987) . The decision to grant or deny permanent injunctive relief is an act of equitable discretion by the district court, reviewable on appeal for abuse of discretion. See, e.g., Romero-Barcelo, 456 U. S., at 320.

These familiar principles apply with equal force to disputes arising under the Patent Act. As this Court has long recognized, “a major departure from the long tradition of equity practice should not be lightly implied.” Ibid.; see also Amoco, supra, at 542. Nothing in the Patent Act indicates that Congress intended such a departure. To the contrary, the Patent Act expressly provides that injunctions “may” issue “in accordance with the principles of equity.” 35 U. S. C. §283. 2

(From the Opinion of the Court delivered by Justice Thomas.)