Slowly, too slowly, the federal courts are chipping away at President Bush’s unbridled assertion of presidential power as long as it’s done in the name of the war on terrorism.

In a 2-to-1 decision, a federal appeals court in Richmond, Va., ruled that the president cannot indefinitely imprison without trial or charges a legal U.S. resident merely on suspicion.

“To sanction such presidential authority to order the military to seize and indefinitely detain civilians, even if the president calls them enemy combatants, would have disastrous consequences for the Constitution — and the country,” Judge Diana Motz wrote.

The case involves Ali al-Marri, a Qatari national, legally in the United States on a student visa with his family to study at Bradley University in Peoria, Ill. He was arrested in December 2001 on charges of credit-card fraud and lying to investigators. His trial was pending when, in 2003, he was declared an enemy combatant, turned over to the military and imprisoned in a Navy brig where for the next 16 months he was held incommunicado, barred from contacting his family or his lawyer. An earlier lawsuit alleges that the time was used to subject al-Marri to brutal interrogation techniques.

The Bush administration says that al-Marri had trained at an Osama bin Laden camp in Afghanistan and that 9/11 mastermind Sheikh Khalid Mohammed identified him as an al Qaeda sleeper agent sent here to one day disrupt the U.S. financial system.

That certainly sounds serious, but in the absence of a court proceeding we have only the Bush administration’s say-so.

Al-Marri’s case is one of three in which U.S. citizens or residents were thrown into military prisons with no right of court appeal.

Faced with certain defeat in the Supreme Court, the administration plucked Jose Padilla out of a military prison and turned him over to the civilian criminal justice system. Padilla, whom the administration initially said was plotting to set off radioactive bombs, was charged with a couple of counts of criminal conspiracy.

Yaser Esam Hamdi was a young Saudi who had been born in the United States. Taken prisoner in Afghanistan, he was locked up in Guantanamo with the “worst of the worst” before being transferred to a Navy brig. When Hamdi began to win his court challenges, the administration quietly returned him to Saudi Arabia and his father.

The court’s rebuff of this expansive view of presidential power is one more step in returning the country to where the Constitution says it should be.