Legal Definitions - Anti-Injunction Act

The Anti-Injunction Act is a federal law that limits the power of federal courts to issue injunctions in certain situations.

Under the Anti-Injunction Act, a federal court cannot stop or "enjoin" a state court proceeding unless:

1. Congress has expressly authorized the injunction
2. The injunction is necessary for the federal court's jurisdiction over a particular piece of property
3. The injunction is necessary to prevent the re-litigation of a judgment already rendered by the federal court

For example, if a state court is hearing a case involving a contract dispute, a federal court cannot issue an injunction to stop the state court from proceeding unless one of the three conditions above is met.

The Anti-Injunction Act is related to another federal law called the Norris-La Guardia Act. The Norris-La Guardia Act limits the power of federal courts to issue injunctions in labor disputes. The purpose of the Norris-La Guardia Act is to promote collective bargaining and prevent employers from using injunctions to stop union activity.

For example, if a group of employees goes on strike to protest working conditions, their employer cannot ask a federal court to issue an injunction to force them back to work unless the employer meets certain requirements under the Norris-La Guardia Act.