Younger v. Harris

Harris (plaintiff) was indicted in California state court under the state's Criminal Syndicalism Act for promoting a form of socialism. Rather than raise his First and Fourteenth Amendment defenses in the pending state prosecution, he sued in federal court to enjoin the district attorney, Younger (defendant), from prosecuting him, arguing the Act was unconstitutional. The federal district court agreed, found the Act unconstitutional, and enjoined the state prosecution.

Whether federal courts must abstain from enjoining pending state criminal proceedings unless there is a showing of a great and immediate threat of irreparable injury due to an unconstitutional statute.