SIX years ago this Tuesday, President Bush granted American armed forces sweeping authority to detain and interrogate foreign members of Al Qaeda and their supporters and to use military commissions to try them. By doing so, the president set in motion the creation of military commissions and the detention camp in Guantánamo Bay, Cuba.

The Bush administration may legitimately claim certain benefits from the Guantánamo system. Some dangerous men are held there, and valuable intelligence has probably been gathered, perhaps even some that has enabled the government to disrupt terrorist activities.

But the costs have been high. Guantánamo has come to be seen worldwide as a stain on America’s reputation. The military commissions have failed to deliver justice, stymied by the federal courts’ refusal to permit the president to create a system at odds with United States courts-martial and the international law of war.

Meanwhile, the number of detainees at Guantánamo has steadily dropped to a little over 300, from its peak of more than 700, no more than 80 of whom are likely to face any kind of American prosecution. Not a single defendant has gone to trial, and only one has pleaded guilty.