He became the voice for a type of tough justice that harked back to the Wild West, when the lawman's word was absolute and few worried about the rights of prisoners or immigrants.

On Tuesday, Arpaio faced what may be his most demanding and dangerous opponent: U.S. District Judge G. Murray Snow, who will decide whether the man who has called himself "America's toughest sheriff" should be held in contempt for deliberately ignoring court orders in a long-running civil rights case.

"He has been trying to get out of this desperately," Alessandra Soler, executive director of the American Civil Liberties Union of Arizona, said in an interview on Tuesday, the first of what is expected to be four days of hearings in Phoenix. "He has been hiding behind the badge and that's why it is very, very important to have a public trial."

Arpaio has refused to comment on the current proceeding, which could result in a fine and perhaps a criminal case down the road. The sheriff is on the witness list of about two dozen people but is not expected to testify until later in the week.