Preliminary Injunctions and Temporary Restraining Orders

Preliminary injunctions and temporary restraining orders (TROs) are two forms of emergency equitable relief available in U.S. courts that allow a judge to compel or prohibit action before a case reaches final judgment. This page covers their definitions, the procedural mechanisms governing them, the contexts in which courts most frequently apply them, and the legal standards that determine when relief is granted or denied. Understanding these tools is essential to grasping how courts manage urgent disputes within the broader civil litigation process.

Definition and scope

A preliminary injunction is a court order issued after notice to the opposing party and an opportunity for a hearing, directing a party to act or refrain from acting during the pendency of litigation. A temporary restraining order is a shorter-duration emergency measure that may be issued without notice to the opposing party under strictly limited circumstances.

Both forms of relief are classified as equitable remedies, meaning they derive from the court's equity powers rather than from the award of money damages. In the federal system, the governing authority is Federal Rule of Civil Procedure 65 (FRCP Rule 65), which sets out the procedural requirements for both instruments. State courts maintain analogous rules, though the specifics vary by jurisdiction. The scope of injunctive relief more broadly — including permanent injunctions — is addressed in the companion reference on injunctions and equitable relief in U.S. courts.

A TRO, by default under FRCP Rule 65(b)(2), may not exceed 14 days, though a court may extend it for good cause or by the consent of the parties. A preliminary injunction, by contrast, remains in effect until the court issues a final judgment or dissolves the order, which in complex litigation can span months or years.

How it works

The procedural pathway for obtaining a preliminary injunction or TRO follows discrete steps:

1. Filing the motion — The moving party files a motion for a TRO or preliminary injunction, typically accompanied by a memorandum of law, declarations or affidavits establishing the factual basis, and a proposed order. This occurs within the framework of pretrial motions in U.S. courts.

2. Ex parte consideration (TRO only) — Under FRCP Rule 65(b)(1), a TRO may be issued without notice only if the moving party demonstrates by specific facts in an affidavit or verified complaint that immediate and irreparable injury will result before the opposing party can be heard, and that efforts to provide notice were made or explain why notice should not be required.

3. Notice and hearing (preliminary injunction) — The court must set a hearing date for a preliminary injunction. The opposing party receives notice and may submit evidence in opposition. Courts frequently permit limited expedited discovery before the hearing.

4. Ruling — The court applies the governing four-factor test (detailed below) and issues a written order. If a TRO was previously granted, the preliminary injunction hearing must occur before the TRO expires unless extended.

5. Security requirement — Under FRCP Rule 65(c), the court must require the moving party to post a security bond in an amount sufficient to cover costs and damages that may be incurred by the opposing party if it is later found that the injunction was wrongfully issued.

6. Appeal — Under 28 U.S.C. § 1292(a)(1), interlocutory orders granting or refusing preliminary injunctions are immediately appealable to the courts of appeals, an exception to the general final-judgment rule.

Common scenarios

Preliminary injunctions and TROs appear across a wide range of substantive disputes. The most frequently litigated categories include:

• Intellectual property — Parties seek to prevent ongoing infringement of patents, trademarks, or copyrights while the merits are litigated. The U.S. Court of Appeals for the Federal Circuit regularly reviews such orders in patent matters.
• Trade secrets and noncompete agreements — Employers seek orders preventing former employees from using proprietary information or competing in violation of contractual obligations.
• Constitutional and civil rights challenges — Plaintiffs challenge enforcement of statutes or regulations alleged to violate constitutional rights, a context explored in constitutional litigation in U.S. courts and the civil rights litigation framework. Courts in this category have enjoined the enforcement of state statutes pending appellate review.
• Regulatory disputes — Regulated entities challenge agency rules or enforcement actions before final agency disposition. The Administrative Procedure Act (5 U.S.C. § 705) explicitly authorizes courts to stay agency action pending review, which intersects with the TRO and preliminary injunction framework.
• Domestic relations and family law — State courts issue TROs in the context of protective orders under statutes such as the Violence Against Women Act (34 U.S.C. § 12291 et seq.), which conditions federal funding on state compliance with minimum protective order standards.
• Real property and environmental disputes — Courts issue orders preventing imminent physical alteration of property or environmental harm while ownership or liability is contested.

Decision boundaries

Federal courts apply a four-factor balancing test derived from the Supreme Court's decision in Winter v. Natural Resources Defense Council, 555 U.S. 7 (2008), which displaced earlier, more permissive circuit-level formulations. The four factors are:

1. Likelihood of success on the merits — The moving party must demonstrate a substantial probability of prevailing at trial, not merely that the case raises serious questions.
2. Irreparable harm — The moving party must show that it will suffer irreparable injury in the absence of relief. Purely economic harm that can be compensated through money damages generally does not satisfy this element, as addressed in damages in U.S. litigation.
3. Balance of equities — The court weighs the harm to the moving party against the harm that the injunction would cause the opposing party.
4. Public interest — The court considers whether issuing the order serves or disserves the public interest, a factor that carries particular weight when government parties or broadly applicable regulations are involved.

The Ninth Circuit and certain other circuits previously permitted a "sliding scale" approach under which a stronger showing on one factor could compensate for a weaker showing on another. Winter imposed a higher floor, requiring at least a threshold showing on each factor rather than permitting full substitution. The circuit courts remain split on the precise weight given to each factor in specific doctrinal contexts.

TRO vs. Preliminary Injunction — Key Distinctions:

A court that grants or denies a summary judgment motion does not render a prior preliminary injunction moot — the injunction remains effective unless expressly modified or dissolved. Courts treat the preliminary injunction standard and the summary judgment standard as analytically distinct, since the former involves probabilistic prediction about trial outcome while the latter resolves the merits as a matter of law.

Standing to sue is a threshold constitutional requirement that applies to preliminary injunction motions no less than to final merits adjudication. A movant that lacks Article III standing cannot obtain emergency equitable relief, and federal courts raise standing defects sua sponte.

References

• Federal Rule of Civil Procedure 65 — Cornell Legal Information Institute
• 28 U.S.C. § 1292 — Interlocutory Decisions — Cornell Legal Information Institute
• Winter v. Natural Resources Defense Council, 555 U.S. 7 (2008) — Supreme Court of the United States
• Administrative Procedure Act, 5 U.S.C. § 705 — Cornell Legal Information Institute
• Violence Against Women Act, 34 U.S.C. § 12291 — Cornell Legal Information Institute
• U.S. Courts — Federal Rules of Civil Procedure
• U.S. Court of Appeals for the Federal Circuit — Official Site