An amicus brief, short for amicus curiae or friend of the court, lets a non-party offer a perspective that the parties may not fully present. Industry groups, researchers, civil-rights organizations, economists and government bodies sometimes submit these briefs in cases with effects beyond the immediate dispute.
The brief may explain technical background, discuss possible consequences of a ruling or argue for one interpretation of the law. In a competition case, an amicus might address how a proposed remedy would affect publishers, advertisers, small companies or consumers. Its arguments are submissions to the court, not evidence that the claims have been proved.
Courts control whether and how non-parties may participate. Depending on the court and procedural stage, an amicus may need consent or permission to file. Parties can respond to the arguments, and judges remain free to agree, disagree or give the filing little weight. An amicus is not automatically neutral simply because it is not a named plaintiff or defendant.
To evaluate an amicus brief, identify who filed it, who supports the organization, the position it advocates and which court or appeal it addresses. Read the court's eventual opinion separately to learn whether the judges actually relied on its reasoning.