The Federal Circuit, which is often the court of last resort in patent disputes because the U.S. Supreme Court accepts so few cases for review, has developed a line of authority under which plaintiffs who establish patent validity and infringement enjoyed a presumption in favor of injunctive relief “absent exceptional circumstances.”
However, in eBay Inc. v. MercExchange, L.L.C., No. 05-130 (May 15, 2006), the U.S. Supreme Court held that the four-factor test traditionally applied by courts of equity in deciding whether or not to grant injunctive relief applied equally to disputes arising under the Patent Act.
Regardless of the fact that a case involves alleged patent infringement, a district court should not issue an injunction unless it finds (1) that plaintiff 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.