Jose Padilla, the alleged Al Qaeda operative held as an "enemy combatant" for more than three years, made his first appearance in court Thursday after he was taken from a Navy brig and flown to Miami.

The transfer from military to civilian custody began after a legal battle that went all the way to the Supreme Court.

Padilla appeared before a judge on criminal charges after he was taken from a brig in South Carolina and flown by military aircraft to Miami, said U.S. Marshals Service spokesman Dave Turner. He is to enter a plea Friday.

At the brief hearing, U.S. Magistrate Judge Barry Garber explained Padilla's rights as a criminal defendant and asked whether he understood them.

"Yes, I do," said Padilla, dressed in an orange prison jumpsuit and shackled at the wrists and ankles. He wore glasses and had a short haircut.

Garber set a Friday afternoon hearing for Padilla to enter his plea and to determine whether he will remain in custody or be released on bail. Prosecutors said they would seek for him to be held before his trial.

Padilla, a former Chicago gang member, was arrested at Chicago's O'Hare Airport in May 2002 and held by the Bush administration without criminal charges on suspicion of plotting to detonate a radioactive "dirty bomb" inside the United States.

The U.S. Supreme Court has been asked to use Padilla's case to define the extent of presidential power over U.S. citizens who are detained on American soil on suspicion of terrorism. But before the high court could decide whether take up the case, the Bush administration indicted Padilla in November in civilian court.

The charges do not involve the "dirty bomb" allegations, contending instead that Padilla joined a North American terror support network that sent him overseas to train with Al Qaeda and to "murder, maim and kidnap" people on foreign soil.

The transfer of Padilla from military to civilian custody was approved Wednesday by the Supreme Court, which overruled the 4th U.S. Circuit Court of Appeals.

The appeals court had refused to allow the transfer in a decision sharply critical of the Bush administration. It suggested the administration changed tactics and indicted Padilla to avert a ruling from the Supreme Court on presidential powers during wartime.