Soon after the Sept. 11, 2001, attacks, the Bush administration faced a fateful choice about terrorist detainees: Should it get Congress on board, or go it alone? President George W. Bush bypassed the legislature and for seven years based U.S. detention policy on his own constitutional authority, Congress' general authorization for the war against al-Qaida and its affiliates, and the international laws of war. Working with Congress would be hard, administration officials reasoned; the legislature might constrain executive flexibility; and the president had powerful arguments that he didn't need additional legislative support.

Today, President Obama faces much the same choice, and he appears sorely tempted to follow the same road, for the same reasons: "White House officials are increasingly worried that reaching quick agreement with Congress on a new detention system may be impossible," The Post reported Saturday, and "Congress may try to assert too much control over the process."

Obama, to put it bluntly, seems poised for a nearly wholesale adoption of the Bush administration's unilateral approach to detention. The attraction is simple, seductive and familiar. The legal arguments for unilateralism are strong in theory; past presidents in shorter, traditional wars did not seek specific congressional input on detention. The unilateral approach lets the president define the rules in ways that are convenient for him and then dares the courts to say no.

This seductive logic, however, failed disastrously for Bush — and it will not serve Obama any better. Bush's approach avoided congressional meddling but paradoxically sloughed off counterterrorism policy on the courts. Over time, the judiciary grew impatient with ad hoc detention procedures that lacked clear and specific legislative authorization, and judges began imposing novel and increasingly demanding rules on the commander in chief's traditionally broad powers to detain enemy soldiers during war.

The result has been nearly eight years of unstable policy with no safe harbor for executive conduct and no settled rules for detainees. Ironically, one of the biggest casualties of this misadventure was the executive authority the Bush administration held so dear. At least in detention policy, Bush left a weaker presidency than he inherited, one encumbered by unprecedented restrictions imposed by judges.

In the short term, Obama may get away with a unilateral executive detention scheme. His personal prestige is high. He can dress up his detention plan as a narrowing of Bush's policy. It will apply to fewer detainees than Bush's policy and at a facility not named Guantanamo Bay.

But refusing to go to Congress still leaves inexpert and unaccountable courts to decide the details of our detention policy. Courts will not defer forever to the notion that the government can lock up people indefinitely on the say-so of the president, and, as time passes, they will continue their march toward peacetime criminal-justice standards for wartime detainees. Hard trade-offs between liberty and security will be made haphazardly and without democratic legitimacy.

The president can still get what he needs on detention if he works from Congress' bipartisan center, if he releases more substantial information about the detainees he thinks cannot be set free and if he speaks often — as he did at the National Archives recently — about the need for stable rules to govern noncriminal detentions that America cannot forswear. Presidential insistence on detention legislation will force members of Congress to take a stand and will minimize congressional carping down the road. The process of crafting this legislation would spark a debate that would educate the country about the threat we face and would legitimate policies emerge from the process.

Benjamin Wittes is a senior fellow at the Brookings Institution. Jack Goldsmith teaches at Harvard Law School and served as an assistant attorney general in the Bush administration. They wrote this commentary for The Washington Post.