IN THE PAST few weeks the presidential candidates have debated almost every aspect of the war on terrorism save one: the handling of detainees in Iraq and Afghanistan. That is a remarkable omission, if only because the shocking photographs of abuses at Abu Ghraib prison in Iraq, and reports of hundreds of other cases of torture and homicide in Iraq and Afghanistan, have done grave damage to the United States' ability to combat extremism in the Muslim world. There is, too, something important to debate: whether the United States will return to adhering to the Geneva Conventions and other international rules governing the treatment of foreign prisoners, or whether the war on terrorism justifies the violation of international law in certain cases. President Bush clearly intends to preserve the current, exceptional policies he adopted after Sept. 11, 2001, despite the abuses to which they led. Sen. John F. Kerry has criticized the abuses but hasn't made clear whether he would change the policies.

Mr. Bush is obviously eager to avoid the subject of prisoner detentions. Maybe that's because his public stance on what happened at Abu Ghraib, and what caused it, is entirely at odds with the facts brought out by official investigations. When he last spoke of the matter, months ago, the president maintained that the abuse was the responsibility of a few low-ranking soldiers working the night shift. He has not acknowledged that scores of soldiers have now been implicated for crimes including homicide, or that a Pentagon-appointed panel has found responsibility at senior levels of the Pentagon, the Justice Department and the White House. Nor has he held anyone in his administration accountable. Defense Secretary Donald H. Rumsfeld, who made policy decisions about interrogations that led directly to the abuse of prisoners in Afghanistan and Iraq, said he's not aware that any abuses occurred during questionings -- even though an official report by his own department confirmed that very point.

The administration's guilty silence has been abetted in the past month by Pentagon and congressional investigators. Several Republican senators have said that there are major outstanding issues of both fact and accountability: for example, the role of the CIA in introducing abusive interrogation techniques into Iraq and illegally hiding prisoners from the International Red Cross. But no congressional hearings have been held on the issue in more than a month. At the last hearings, on Sept. 9, officials said a major Pentagon investigation covering a crucial subject -- how abusive and illegal interrogation policies spread through Afghanistan and Iraq -- was mostly completed and would be released by the end of September. Conveniently for the president's reelection campaign, it has yet to appear.

The record of prisoner abuse stands as a principal count in any indictment of the Bush administration's handling of Iraq and the war on terrorism. Yet Mr. Kerry, who has devoted much of his campaign in the past month to criticizing how Mr. Bush has handled the war, has barely mentioned Abu Ghraib. A couple of months ago the Democrat said he felt "revulsion" over the prisoner abuses (Mr. Bush has said the same) and called for Mr. Rumsfeld's resignation. What he hasn't said is whether he accepts or rejects the policy decisions that led to it -- most importantly, Mr. Bush's contention that some detainees captured abroad should not be treated according to the standards of the Geneva Conventions but instead can and should be subjected to harsh treatments long rejected by the U.S. military. Whether that policy is to be perpetuated in spite of the harm it has caused ought to be something about which both Mr. Kerry and Mr. Bush speak clearly; their answers ought to help inform voters' decisions.