FILE - In this Nov. 6, 1979 file photo, students stand guard before the entrance of the United States Embassy where staff is being held hostage in Tehran, as a portrait of Ayatollah Khomeini is on display. The Obama administration asked a federal judge Tuesday, April 21, 2009 to throw out a lawsuit against Iran filed by Americans held hostage at the embassy in Tehran 30 years ago. In court papers filed Tuesday night, the Justice Department argued that the agreement to release the hostages precluded lawsuits against Iran. (AP Photo/File)