The preliminary injunction is an equitable remedy that may be granted to prevent harm to a movant before adjudication on the merits can be reached. The United States Supreme Court most recently iterated in Winter v. National Resource Defense Counsel, Inc. the four factors a court must consider for a preliminary injunction to issue.[1] A movant seeking a preliminary injunction must establish that the movant is likely to succeed on the merits; that the movant is likely to suffer irreparable harm in the absence of preliminary relief; that the balance of equities tips in the movant’s favor; and that an injunction is in the public interest.[2] Federal circuits have long been split over how to apply these factors and what kind of test these factors create. Following Winter, there is still no consensus. The circuits apply three different tests to preliminary injunction questions: the sequential test, the sliding scale test, and the gateway factor test.

Circuits that apply the sequential test require a movant to prove each of the four factors in turn, and a failure to prove one factor bars injunctive relief. Circuits that apply the sliding scale test balance all four factors, and a higher showing on one factor can make up for a lesser showing on another factor. Circuits that apply the gateway factor test require movants to demonstrate a likelihood of success on the merits and a likelihood of suffering irreparable harm in the absence of preliminary relief before addressing the remaining two elements. Under this approach the first two factors are dispositive.

This article argues that the sliding scale test is the most appropriate test when determining whether to issue a preliminary injunction. The history of equity in the United States supports this assertion. Further, the Supreme Court has historically endorsed the sliding scale test.

[1] 555 U.S. 7 (2008).

[2] Winter v. Natural Res. Def. Council, Inc., 555 U.S. 7, 20 (2008) (Ginsburg, J., dissenting) (citing Munaf v. Geren, 553 U.S. 674, 689–90 (2008); Amoco Prod. Co. v. Village of Gambell, 480 U.S. 531, 542 (1987); Weinberger v. Romero-Barcelo, 456 U.S. 305, 311–12 (1982)).