How to Enjoin Enforcement: Four-Factor Test, Filing, and Appeals

To enjoin enforcement of a law, you file a motion in court — usually for a preliminary injunction — and prove four things: you are likely to win the underlying case, you will suffer irreparable harm without the order, the hardships tip in your favor, and blocking the law serves the public interest. Before the court will even consider those factors, you have to show you have standing to sue, and you have to clear procedural hurdles including sovereign immunity and, in most cases, an injunction bond. An injunction is one of the strongest checks the judiciary holds over legislative and executive power, and courts set the bar high before granting one.

Who Can Sue: Standing to Seek an Injunction

Standing is the threshold. You need a personal, concrete stake: an actual injury (not a hypothetical one), traceable to the law you are challenging, that a court order can fix.¹

Because an injunction is forward-looking, the bar is higher than for damages cases. You must show the threatened harm is “certainly impending” or that there is a “substantial risk” the law will be enforced against you.¹ Past injury alone will not do it. Someone harmed by a law last year who faces no ongoing or future threat cannot get an injunction and must pursue damages instead. Many challenges stall here before reaching the merits.

Which Kind of Injunction to Request

Three forms of injunctive relief exist, and the right choice depends on how urgent your situation is and how far the case has progressed.

A temporary restraining order is the fastest. A court can issue one without the other side present if sworn statements show that waiting for a hearing would cause immediate and irreparable harm. It expires within 14 days unless the court extends it for good cause.²

A preliminary injunction requires a full adversarial hearing with evidence from both sides. If granted, it stays in force throughout the litigation. This is the usual vehicle for stopping enforcement of a law while the constitutional or statutory arguments play out, and it is where the four-factor test governs.

A permanent injunction comes only after a full trial in which you have proven your case on the merits. It is meant to last indefinitely, though courts can modify or dissolve it if the law changes or the facts shift.

The Four-Factor Test

The Supreme Court’s decision in Winter v. Natural Resources Defense Council set the test every federal court applies. You must show you are likely to succeed on the merits, likely to suffer irreparable harm without the injunction, that the balance of hardships tips in your favor, and that the injunction serves the public interest.³ Weakness on any factor can sink the request.

Likelihood of Success on the Merits

You must show a genuine probability of winning, not just a possibility. The Supreme Court has been explicit that “likely to succeed” means what it says, and a speculative or remote chance does not qualify.³ The court is not deciding the case at this stage, but it is making a preliminary assessment of your legal theory. Because duly enacted laws carry a presumption of validity, courts often scrutinize this factor closely.

This is usually the factor that makes or breaks the motion. A strong legal theory can survive modest weakness elsewhere; a shaky one will almost always doom the request no matter how much harm the law is causing.

Irreparable Harm

Irreparable harm is injury that money cannot adequately fix after the case ends. The harm must be likely, not merely possible; the Supreme Court rejected a looser standard as too lenient.³ It also has to be imminent.

When a law allegedly violates constitutional rights, this factor is often easy to satisfy. The Supreme Court has recognized that the loss of First Amendment freedoms, even for brief periods, is irreparable by its nature.⁴ Similar reasoning applies to other fundamental rights. Financial injury alone is harder to establish as irreparable, because courts generally view monetary losses as fixable through damages — unless the financial harm threatens to destroy a business or livelihood entirely.

Balance of Hardships

The court compares what happens to you if the law stays in force against what happens to the government and the public if enforcement stops. If a law threatens to shut down your business permanently, that hardship probably outweighs the government’s interest in enforcing a statute of uncertain validity for a few more months. But if halting the law would create public safety risks, disrupt regulatory frameworks, or cost the government substantial revenue, the calculus shifts. Courts are especially cautious when the challenged law serves a protective function such as consumer safety, environmental, or public health measures.

Public Interest

The final factor asks whether the public at large benefits from pausing the law. Two competing interests are always in play: orderly enforcement of laws, and protection of constitutional rights. When a law appears to violate established constitutional principles, courts generally find that blocking it serves the public interest. When the constitutional question is close and the law addresses a genuine public need, this factor can tilt the other way.

Circuit Differences That Can Change the Outcome

The Winter framework is the baseline, but not every federal circuit applies it identically. The Second, Fifth, Seventh, and Ninth Circuits use a sliding scale, where an especially strong showing on one factor can compensate for a weaker showing on another. Under that approach, raising “serious questions” about the merits and showing that the balance of hardships tips sharply your way can be enough, even without a clear probability of winning. The Fourth, Tenth, and Eleventh Circuits reject the sliding scale and require a solid showing on all four factors independently. The D.C. Circuit has not definitively resolved whether the sliding scale survived Winter.

Where you file can meaningfully affect the outcome. A challenge that would succeed in the Ninth Circuit might fail in the Eleventh under the same facts.

Suing the Government: Sovereign Immunity Workarounds

Suing the government adds an obstacle. The Eleventh Amendment bars most suits against states in federal court, which would seem to make injunctions against state laws impossible. The workaround comes from Ex parte Young, a 1908 Supreme Court decision holding that a state official who enforces an unconstitutional law is acting outside the state’s authority and can be sued personally for an injunction.⁵ Your suit must name a specific official with a connection to enforcement; you cannot sue the state itself or an unrelated official.

For challenges to state and local officials who violate constitutional rights, 42 U.S.C. § 1983 provides a direct cause of action against any person who, acting under state authority, deprives someone of federally protected rights.⁶ Injunctive relief is explicitly available. If the defendant is a judge, you must first obtain or attempt to obtain a declaratory judgment before seeking an injunction.

A separate barrier applies when you ask a federal court to block proceedings in a state court. The Anti-Injunction Act generally prohibits that, with three narrow exceptions: where Congress has expressly authorized it, where the injunction is necessary to protect the federal court’s own jurisdiction, or where it protects a prior federal judgment.⁷

How to File the Motion

Filing starts with a formal motion supported by a legal brief that walks through each of the four factors. Generalized assertions of harm will not work. The motion needs specific factual evidence — usually sworn affidavits or declarations describing the concrete, imminent injury you face.

The court then schedules an expedited hearing. It is not a full trial. Judges typically decide on the written submissions rather than live testimony. The government files its own brief and counter-declarations, both sides argue, and decisions often come quickly.

One procedural requirement trips up many challengers: the injunction bond. Federal Rule 65(c) requires the party seeking an injunction to post security that would protect the opposing party from losses if the injunction turns out to have been wrongly granted. Courts have discretion to reduce or waive the bond for plaintiffs who cannot afford it. The federal government and its agencies are exempt from the bond requirement entirely when they seek injunctive relief.²

What the Order Covers

Every injunction must state why it was issued, spell out its terms specifically, and describe in reasonable detail the acts being blocked, without just pointing back to the complaint. Vague orders get overturned. The order binds the named parties, their officers, agents, employees, and attorneys, and anyone else acting in coordination with them who has actual notice of the order.² The government cannot sidestep an injunction by handing the same enforcement action to a different official.

A preliminary injunction lasts until trial concludes, at which point it dissolves or converts into a permanent injunction. Permanent injunctions can be modified later if the law changes or the underlying facts shift enough to justify reopening the order.

Universal Injunctions Are No Longer Available

For years, district courts occasionally issued “nationwide” or “universal” injunctions that blocked enforcement of a law against anyone, not just the named plaintiffs. In 2025, the Supreme Court effectively ended the practice. In Trump v. CASA, Inc., the Court held that federal courts issuing injunctions under the authority of the Judiciary Act of 1789 may award only plaintiff-specific relief, reasoning that universal injunctions lack historical basis in equity, intrude on the executive branch, and circumvent the procedural safeguards of class action rules.⁸

An injunction can now protect the people who brought the lawsuit but generally cannot shield nonparties from the same law. To reach a broader group, you need to file a class action and satisfy certification requirements, or multiple plaintiffs in different jurisdictions must bring separate lawsuits.

Appeals and Emergency Stays

An order granting or denying a preliminary injunction can be appealed immediately, without waiting for the case to end. Federal law specifically authorizes interlocutory appeals of injunction orders.⁹ The right is optional; the losing party can also wait and challenge the injunction as part of a later appeal from the final judgment. Temporary restraining orders generally cannot be appealed under this provision because they are too short-lived and preliminary to qualify.

While an appeal is pending, the government frequently asks the appellate court or the Supreme Court for a stay to pause the injunction and allow enforcement to resume. The stay standard mirrors the injunction test: likelihood of success on appeal, irreparable harm without a stay, no substantial harm to the other side, and consistency with the public interest.¹⁰ In high-profile challenges to executive action, the Supreme Court has increasingly stepped in at this stage to grant emergency stays, sometimes before the appeals court has ruled.

Attorney Fees

Winning an injunction against enforcement of an unconstitutional law can be expensive, and challengers often expect to recover attorney fees. In civil rights cases, federal law allows a court to award reasonable attorney fees to the prevailing party.¹¹ The question is what “prevailing party” means.

In 2025, the Supreme Court narrowed the definition. In Lackey v. Stinnie, the Court held that obtaining a preliminary injunction alone does not make someone a prevailing party eligible for fees. You prevail only when a court conclusively resolves the claim by granting enduring relief on the merits that permanently alters the legal relationship between the parties.¹² A preliminary injunction preserves the status quo based on a prediction of likely success; it does not conclusively decide anything. If the case later becomes moot before final judgment, the challenger walks away with no fee recovery despite the preliminary win. Budget for the full cost of litigation through final judgment; relying on a preliminary injunction victory to fund the case through fee-shifting is no longer viable.

Consequences of Disobeying the Order

Disobeying an injunction — temporary, preliminary, or permanent — is contempt of court. Federal courts have inherent authority to punish contempt, a power rooted in the Judiciary Act of 1789.¹³ Civil contempt is designed to coerce compliance through escalating fines or other sanctions until the violator obeys; the violator can purge the contempt by complying. Criminal contempt punishes the completed violation to vindicate the court’s authority and can result in fines or imprisonment that later compliance will not undo.

Government officials face the same exposure. An injunction does not become optional because the enjoined party disagrees with it or believes it was wrongly issued. The proper response is to appeal, not to defy the order.

1
Legal Information Institute. U.S. Constitution Annotated – Standing Requirement Overview
2
Legal Information Institute. Federal Rules of Civil Procedure Rule 65 – Injunctions and Restraining Orders
3
Justia Law. Winter v. Natural Resources Defense Council, Inc., 555 U.S. 7 (2008)
4
Justia Law. Elrod v. Burns, 427 U.S. 347 (1976)
5
Federal Judicial Center. Ex parte Young (1908)
6
Office of the Law Revision Counsel. 42 U.S. Code 1983 – Civil Action for Deprivation of Rights
7
Office of the Law Revision Counsel. 28 U.S. Code 2283 – Stay of State Court Proceedings
8
Supreme Court of the United States. Trump v. CASA, Inc. (2025)
9
Office of the Law Revision Counsel. 28 U.S. Code 1292 – Interlocutory Decisions
10
Legal Information Institute. Nken v. Holder (2009)
11
Office of the Law Revision Counsel. 42 U.S. Code 1988 – Proceedings in Vindication of Civil Rights
12
Supreme Court of the United States. Lackey v. Stinnie (2025)
13
Congress.gov. Constitution Annotated – Inherent Powers Over Contempt and Sanctions