A motion for a preliminary injunction is a pretrial request asking a court to order the opposing party to stop, or start, doing something while the lawsuit is still pending. Courts treat it as an extraordinary remedy because it restricts a party’s conduct based on claims that haven’t been proven at trial. To get one, the movant has to clear a demanding four-factor legal test, give notice to the other side, and almost always post a security bond to protect that party if the order turns out to have been wrongly issued.
The Four-Factor Test
The Supreme Court set the modern framework in Winter v. Natural Resources Defense Council, Inc. (2008). A plaintiff must establish all four of the following:1Cornell Law Institute. Winter v. Natural Resources Defense Council, Inc.
- Likelihood of success on the merits. The movant has to show the court enough evidence and legal reasoning that they will probably win at trial. A plausible theory alone is not enough.
- Likelihood of irreparable harm. The movant must demonstrate an injury that money cannot fix after the fact. Winter rejected the older “possibility” standard; the harm must be likely. Common examples include disclosure of trade secrets, destruction of unique property, and the loss of constitutional freedoms.
- Balance of equities. The court weighs the hardship the movant faces without the injunction against the hardship the opposing party faces if it is imposed.
- Public interest. The court considers whether the injunction would help or hurt the broader public, not only the two parties in front of it.
All four must favor the movant. Falling short on even one typically sinks the motion.
Courts also distinguish between prohibitory injunctions, which tell someone to stop doing something, and mandatory injunctions, which force an affirmative step. Because a mandatory order changes the status quo rather than preserving it, judges apply a higher standard and usually expect the movant to show extraordinary circumstances on top of the four factors.
Preliminary Injunction vs. Temporary Restraining Order
These two provisional remedies are easy to confuse, but they run on different tracks.
A temporary restraining order is for genuine emergencies. Under Federal Rule of Civil Procedure 65(b), a court can issue a TRO without notice to the opposing party if the movant shows through an affidavit or verified complaint that immediate and irreparable injury will occur before the other side can be heard. The movant’s attorney must also certify in writing what efforts were made to give notice and why notice should not be required.2Legal Information Institute (LII) / Cornell Law School. Temporary Restraining Order A TRO issued without notice expires no later than 14 days after entry, though a court can extend it once for another 14 days on good cause.3Legal Information Institute (LII) at Cornell Law School. Rule 65 Injunctions and Restraining Orders
A preliminary injunction requires notice to the opposing party before the court can issue it. There is no shortcut. The trade-off is longevity: a preliminary injunction has no built-in expiration date and stays in effect until trial, settlement, or further court action.
What You File With the Motion
Preliminary injunction motions are paper-heavy. Judges decide them largely on the written record, so the filing often matters more than the hearing itself. A complete package generally includes:
- The written motion. This is the core legal argument, walking the judge through the four-factor test against the specific facts of the case.
- Supporting declarations or affidavits. These are sworn statements, signed under penalty of perjury, from people with firsthand knowledge. Statements built on secondhand information or speculation carry little weight.
- Exhibits and evidence. Contracts, correspondence, photographs, financial records, or anything else that corroborates the declarations.
- A proposed order. Rule 65(d) requires every injunction to state its terms specifically and describe in reasonable detail the acts restrained or required. Drafting a clean proposed order up front makes it easier for the judge to grant the motion.
- A memorandum addressing the security bond. Because a bond will almost certainly be required, the filing should propose an appropriate amount and support it with evidence.
Once filed, the papers must be formally served on the opposing party, who then gets time to file an opposition with their own declarations and evidence. Their goal is to undercut at least one of the four factors.
The Security Bond Requirement
This is the part that catches many movants off guard. Federal Rule of Civil Procedure 65(c) requires the movant to post a security bond before a preliminary injunction takes effect. The bond protects the opposing party: if the court later determines the injunction was wrongly issued, the bond covers the costs and damages the restrained party suffered in the meantime.3Legal Information Institute (LII) at Cornell Law School. Rule 65 Injunctions and Restraining Orders
The rule gives no formula. Judges set whatever amount they consider proper based on the circumstances, which can mean a nominal sum or hundreds of thousands of dollars in complex commercial disputes. Come prepared with evidence about the potential damages the opposing party could suffer, because the judge will use that estimate to size the bond. The U.S. government and its agencies are exempt from the bond requirement.
If the injunction is eventually found to have been wrongful, the opposing party can recover damages from the bond, but only up to its face value. Recovery is limited to damages actually caused by the restraint, and the restrained party has a duty to mitigate rather than let losses pile up. Speculative or remote harm will not be compensated, and punitive damages generally are not available. The right to recover on the bond usually does not kick in until the case reaches a final resolution on the merits, though a voluntary dismissal by the movant typically triggers it immediately.
Who Must Obey the Order
A preliminary injunction does not bind only the named party. Under Rule 65(d)(2), the order applies to everyone who receives actual notice of it and falls into one of three categories: the parties themselves; their officers, agents, employees, and attorneys; and any other person acting in concert with them.3Legal Information Institute (LII) at Cornell Law School. Rule 65 Injunctions and Restraining Orders
That scope closes an obvious loophole. If a company is enjoined from selling a product and its CEO directs a subsidiary to make the same sales, both the CEO and the subsidiary can be held in violation. The key requirement is actual notice; someone who genuinely does not know about the order cannot be held in contempt for violating it.
What Happens If the Court Grants or Denies It
If the injunction is granted, the judge signs the proposed order, sometimes with modifications, and the movant posts the required bond. The restrained party must comply with the order’s terms until trial, settlement, or further court action. Because the order must describe the prohibited or required acts in reasonable detail, there should be no ambiguity about what the restrained party can and cannot do.
If the injunction is denied, the opposing party remains free to continue the conduct the movant wanted stopped. A denial does not end the lawsuit. It means the movant did not clear the high bar for this particular remedy. The case proceeds, and the movant may still prevail at trial and obtain a permanent injunction at that stage.4LII / Legal Information Institute. Preliminary Injunction
Changing the Order After It Is Issued
A preliminary injunction is not necessarily fixed until trial. If circumstances change significantly after the injunction is issued, the restrained party can file a motion asking the court to modify or dissolve it. Federal Rule of Civil Procedure 60(b)(5) provides a basis for relief from an order when applying it prospectively is no longer equitable.5Law.Cornell.Edu. Rule 60 Relief From a Judgment or Order
In practice, the movant must show that something material has shifted: new legislation changing the legal landscape, a change in the opposing party’s own behavior, or conditions that make compliance genuinely impossible. Courts will not dissolve an injunction simply because the restrained party dislikes it. The burden sits on the party seeking the change, and judges are reluctant to undo an order they just issued unless the new facts are compelling.
Penalties for Violating a Preliminary Injunction
Ignoring a preliminary injunction is one of the fastest ways to end up in serious legal trouble. Under 18 U.S.C. § 401, federal courts have the power to punish contempt of their authority by fine, imprisonment, or both, for disobedience of any lawful court order.6Office of the Law Revision Counsel. 18 US Code 401 – Power of Court
Contempt comes in two forms. Civil contempt is coercive: the court imposes penalties, often escalating daily fines, designed to pressure the violator into compliance, and the sanctions end once the party obeys. Criminal contempt is punitive: it punishes the violation that already occurred, regardless of later compliance, and can result in fixed fines and jail time. Courts have wide discretion in choosing which to apply, and a single violation can trigger both.
The practical point is simple. Even if you believe an injunction was wrongly issued, the correct response is to appeal or move to dissolve it. Violating it while you challenge it is not a defense and will make everything worse.
Appealing the Ruling
Most pretrial rulings cannot be appealed until the case is over. Preliminary injunction decisions are a notable exception. Under 28 U.S.C. § 1292(a)(1), courts of appeals have jurisdiction to hear immediate appeals from interlocutory orders granting, refusing, modifying, or dissolving injunctions.7Office of the Law Revision Counsel. 28 USC 1292 Interlocutory Decisions
The right belongs to both sides. If the injunction is granted, the restrained party can appeal. If it is denied, the movant can appeal. Either way, the appeal is interlocutory, happening while the underlying case continues in the trial court.4LII / Legal Information Institute. Preliminary Injunction
Appellate courts review the trial judge’s decision for an abuse of discretion, a deferential standard. The appeals court does not re-weigh the evidence from scratch; it asks whether the trial judge made a clear error in applying the four-factor test or abused the broad discretion these motions entail. Overturning a preliminary injunction ruling on appeal is possible, but it is an uphill fight.