LAST WEEK, the Senate Armed Services Committee unveiled a new version of legislative provisions governing terrorism suspects. Chairman Carl Levin (D-Mich.) lauded them as an improvement over the originals, which were decried by the Obama administration and even former George W. Bush Defense Department officials as too heavyhanded. In reality, the new proposals are as problematic as the old and should be scrapped.

Since President Obama took office, some lawmakers, including Democrats, have tried to force him to adopt their military-centric approach to fighting terrorism. The original Senate plan permanently banned use of defense funds to build or modify U.S. facilities to hold Guantanamo Bay detainees; ordered military detention for terrorism suspects, including U.S. citizens, captured on U.S. soil; and made it very difficult to transfer detainees deemed fit for release to their homes or third countries. This approach, we have argued, unacceptably limited the president’s flexibility to thwart attacks and react to terrorism threats.

Enter Mr. Levin and the compromise, which is attached to the defense authorization bill. Instead of a permanent ban, the new bill restricts the use of defense funds only for fiscal 2012; the provision, of course, is renewable. The compromise eliminates military detention for U.S. citizens and lawful permanent residents, in most cases, but requires military detention of other suspects captured in the United States. The new plan builds in an escape hatch that allows the defense secretary to waive the requirement if, after consulting with the secretary of state and the director of national intelligence, he determines that it is in the country’s national security interest. This decision must be certified in writing to Congress.

The bill contains one worthy anti-terrorism provision: a reaffirmation of the president’s authority to detain and to use military force against those responsible for the Sept. 11, 2001, attacks, as well as those who are members of or who support al-Qaeda, the Taliban and associated forces.

Congress uses its power over the purse irresponsibly when it steps on the president’s constitutional prerogatives, including where to detain terrorism suspects. This problem is not cured simply because the funding restrictions are enacted year to year. Nor are the transfer restrictions in the new version any more acceptable because they can be waived if the defense secretary virtually guarantees the impossible: that no released detainee will ever return to the fight.

We have criticized the administration for reflexively turning to the federal courts before fully considering military options. This failure was particularly acute in the 2009 case of would-be underwear bomber Umar Farouk Abdulmutallab. But mandatory military detention constitutes an unnecessary and unwise overcorrection; vigorous congressional oversight would be more appropriate.

Mr. Levin played an important role in making the bill less onerous. But it is not enough. Last week the administration threatened a presidential veto of “any bill that challenges or constrains the President’s critical authorities to collect intelligence, incapacitate dangerous terrorists, and protect the Nation.” The president should make good on this promise if the detention provisions survive.