AFTER SEPT. 11, 2001, the legal tools at President Bush's disposal were out of date and did not address the new realities of this different kind of war. He had to confront some difficult choices in the balance between civil liberties and the need to root out terrorist cells at home and abroad. The criticism those choices have sparked has not always been fair. But too often Mr. Bush has overstepped, both in his policy changes and in the way he has pursued them.

Except for winning passage of the USA Patriot Act, Mr. Bush has not generally worked through Congress but has asserted broad executive war powers to take controversial steps on his own. He has not backed down from these positions until forced to by the courts -- thereby, ironically, creating landmark precedents that could hamper the ability of future presidents to take aggressive action to ensure security in emergencies. Both the cause of liberty and the cause of a strong presidency have been harmed.

The Bush administration did not have to hold U.S. citizens as enemy combatants with no semblance of due process and no access to counsel. Nor did it have to hold hundreds of foreign enemy fighters at Guantanamo Bay, Cuba, without creating any formal means of separating innocents from dangerous terrorists. Nor was it wise to set up military tribunals to try war crimes at the base without seeking congressional blessing for rules that are designed to relax certain fair-trial rights. In all of these situations, the administration had powerful and legitimate concerns. Had it been willing to go to Congress, it could have gotten what it needed -- probably with some requirements of fairness and oversight. But Mr. Bush has shown himself so allergic to any form of accountability in this area, so insistent on the executive's power to write its own rules and so committed to secrecy that he created a kind of alternative justice system, one that injured America in the world's eyes and courted the judicial intervention it finally received.

While the Supreme Court has now insisted on reasonable rules to govern detentions in the war on terrorism, Mr. Bush's instincts in this area remain troubling. In a second term, he would probably push not merely for reauthorization of the Patriot Act -- which is reasonable, in the main -- but for aggressive extensions of it.

Gleaning Sen. John F. Kerry's likely approach to civil liberties is somewhat harder, because he has tried to appeal to all sides in the discussion even as he has kept his options open. While he voted for the Patriot Act, for example, he says he has problems with specific sections. Still, his inclination would appear to be more protective of civil liberties than Mr. Bush. He would support the president's power to detain citizens as enemy combatants but not without reasonable process, his campaign says. Sen. John Edwards has said a Democratic administration would redo plans for military tribunals at Guantanamo based on the model of full courts-martial -- an idea that would be attractive if certain practical problems can be overcome. Mr. Kerry would seem likely to apply a more skeptical eye toward increased domestic surveillance and deportation powers. And he would be far more likely than Mr. Bush to seek congressional sanction for the aggressive steps any president would have to take as the war on terrorism proceeded. Any reasonable president will need to make full use of his powers, but that need not mean ignoring the costs to freedom.

This is one in a series of editorials comparing the records and programs of the presidential candidates on important issues. Others can be found at www.washingtonpost.com/opinion.