Translated literally as “friend of the court,” an amicus curiae is a person who—while not technically party to a case—is able to help a court reach a decision by providing information, insight, or expertise on a particular issue. In the instance of Gideon’s case before the Supreme Court, the amicus curiae is actually a collection of lawyers from states across the country who speak in favor of Gideon’s cause. Their informed opinion is used by Fortas as supporting material in his claim.

Betts v. Brady was a landmark ruling by the Supreme Court that denied counsel to indigent defendants in cases where they were being prosecuted by the state. It was ruled upon in 1942 and, for two decades, meant that states did not have a federal requirement to assign a legal counsel to defendants. The ruling was slowly eroded over the years as concessions were made until—in 1963—Gideon v. Wainwright overturned Betts v. Brady.

In the context of the Supreme Court, a brief is a document submitted to the Court that presents the argument of one particular party. A brief is written by the prosecutor and the defendant before the trial and is submitted before the trial begins.