Each U.S. Supreme Court hires several law clerks to assist in the screening of cases in the certiorari pool, writing of memoranda on legal issues, drafting of opinions, and other legal matters. Most of the justices hire four law clerks. Many of the law clerks are recent graduates of prestigious law schools such as Harvard or Yale. Many of the law clerks serve for a U.S. Supreme Court justice after having clerked for a federal circuit court of appeals judge. Most clerks work for a justice for one year, though some will work on two-year terms.