Amicus brief

An amicus brief, from the Latin amicus curiae meaning "friend of the court," is a document filed by someone who is not a party to a lawsuit but has a strong interest in its outcome or expertise on the subject. Trade groups, advocacy organizations, states, scholars and the federal government all file them.

In the Supreme Court, a non-party generally needs the consent of the parties or the Court's permission to file, though governments have an easier path. Briefs may add legal arguments, historical research, empirical data or an account of how a ruling would affect people beyond the parties. Amici are not parties, so they do not argue unless the Court grants time, and they cannot raise issues the parties did not.

Amicus briefs are also a way to signal how many groups care about a case. They may influence whether the Court grants a writ of certiorari, and justices sometimes cite them. Critics worry that well-funded groups can dominate the information the Court sees, and some complain about briefs from groups with undisclosed funding. Briefs do not change the requirement that a litigant have standing.