The Bush administration brought terrorism charges on Tuesday against Jose Padilla in a criminal court after holding him for three and a half years in a military brig as an enemy combatant once accused in a "dirty bomb" plot.

The decision to remove Mr. Padilla from military custody and charge him in the civilian system averts what had threatened to be a constitutional showdown over the president's authority to detain him and other American citizens as enemy combatants without formal charges.

"President Bush has directed his administration to utilize all available tools to protect America from acts of terrorism," Mr. Gonzales said. "This case, which began as an intelligence investigation, is a classic example of why the criminal justice system is one of those important tools."

"The Justice Department cannot continue changing course each time action from the courts is imminent," said Representative Adam B. Schiff, a California Democrat who serves on the Judiciary Committee. "If Congress refuses to act, our judicial policies will continue to be cobbled together in a piecemeal fashion."