U.S. Marshal Nehemiah Flowers said one of the service's responsibilities is to provide a traveling justice with security.
Flowers said Scalia informed marshals that he didn't want any recordings of his speech and when it was discovered that two reporters had tape recorders, one of the marshals took action.
Flowers suggested Friday that Scalia's request should have been publicly announced.
A journalists' advocacy group says that deputy federal marshal, Melanie Rube, violated both the law and the fundamentals of press freedom when she confronted the reporters from The Associated Press and the Hattiesburg American on Wednesday.
The Reporters Committee for Freedom of the Press said in a letter that Rube violated the Privacy Protection Act, which says government officers may not seize materials in the possession of people who plan to distribute them through public communication.
The group is urging that all officials be reminded of the important interests at stake when dealing with the news media.
The letter was addressed to Attorney General John Ashcroft, U.S. Marshals Service Director Benigno Reyna and Flowers.