Amicus briefs

An amicus curiae (literally, friend of the court; plural, amici curiae) is someone who is not a party to a case and is not solicited by a party, but who assists a court by offering information that bears on the case. The decision on whether to admit the information lies at the discretion of the court. The phrase amicus curiae is legal Latin.

The amicus curiae figure originates in Roman law. Starting in the 9th century, it was incorporated into English law, and it was later extended to most common law systems. Later, it was introduced in international law, in particular concerning human rights. From there, it was integrated in some civil law systems (it has recently been integrated into Argentina's law system and Honduras's 2010 civil procedures code). Today, it is used by the European Court of Human Rights, the Inter-American Commission on Human Rights, the Inter-American Court of Human Rights, the Court of Justice of the European Union and the Special Tribunal for Lebanon.

The role of an amicus is often confused with that of an intervener. The role of an amicus is, as stated by Salmon LJ (as Lord Salmon then was) in Allen v Sir Alfred McAlpine & Sons Ltd [1968] 2 QB 229 at p. 266 F-G:

I had always understood that the role of an amicus curiae was to help the court by expounding the law impartially, or if one of the parties were unrepresented, by advancing the legal arguments on his behalf.

The situation most often noted in the press is when an advocacy group files a brief in a case before an appellate court to which it is not a litigant. Appellate cases are normally limited to the factual record and arguments coming from the lower court case under appeal; attorneys focus on the facts and arguments most favorable to their clients. Where a case may have broader implications, amicus curiae briefs are a way to introduce those concerns, so that the possibly broad legal effects of court decisions will not depend solely on the parties directly involved in the case.

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Wikipedia