WASHINGTON, Oct. 9 — The Supreme Court today turned down the chance to elaborate for the first time in more than 50 years on the “state secrets privilege” by refusing to hear an appeal filed on behalf of Khaled el-Masri, who claims he was abducted and tortured by United States agents while imprisoned in Afghanistan.

Without comment, the justices let stand an appeals court ruling that the state secrets privilege, a judicially created doctrine that the Bush administration has invoked to win dismissal of lawsuits that touch on issues of national security, protected the government’s actions from court review.

Mr. Masri, a German citizen of Lebanese descent, says he was detained while on vacation in Macedonia in late 2003, transported by the United States to Afghanistan and held there for five months in a secret prison before being taken to Albania and set free, evidently having been mistaken for a terrorism suspect with a similar name.

Mr. Masri alleges that he was tortured while in the prison. After investigating the case, German prosecutors earlier this year issued arrest warrants for 13 agents of the Central Intelligence Agency. The German Parliament is continuing to investigate the incident, which has become one of the most public examples of the United States government’s program of “extraordinary rendition.”