THIS WEEK, the Senate is likely to take up a defense reauthorization bill that contains several objectionable proposals that would restrict any president’s power to handle terrorism cases. None is more obnoxious than a requirement that terrorism suspects who are not U.S. nationals be held in military custody.

Lawmakers should focus first on this proposal and discard it promptly. Military detention should be an option available to the president, but requiring it in all cases prevents him from taking full advantage of some of the country’s most powerful counterterrorism tools. Law enforcement officials and national security specialists, for example, could be forced to hand over a suspect even if they were making headway in gathering intelligence. This could also thwart the FBI’s ability to surveil a suspected terror ring and gather information for fear that identifying suspects could force it to prematurely capture and hand over these individuals to the military.

Another counterproductive proposal would prohibit the executive branch from using Defense Department funds to construct a U.S. facility or adapt an existing one to hold detainees now at the U.S. naval base in Guantanamo Bay, Cuba. This provision is little more than fear-mongering and ignores the country’s long track record of imprisoning convicted terrorists, including “shoe bomber” Richard Reid, without incident. Lawmakers should also eliminate onerous restrictions on the president’s ability to transfer detainees to their home or third countries.

The bill is on better footing in requiring periodic review to determine whether a detainee should continue to be held because he presents an ongoing threat. But rather than let the defense secretary set up the scheme, the Senate should adopt President Obama’s approach, unveiled this year, which would create a multiagency panel to conduct such reviews. The Senate should ensure that such reviews apply to those captured in the future and not, as the president ordered, only for those currently at Guantanamo.

The bill also wisely updates the Authorization for the Use of Military Force (AUMF), but it should go further. The AUMF blesses the use of military force against al-Qaeda, the Taliban and associated forces responsible for the attacks of Sept. 11, 2011; it also authorizes military action against those who harbored the attackers. The bill reaffirms that authority and specifically authorizes the detention of terrorism suspects. It should make clear that these authorities also apply to spinoff groups that may not have existed in 2001. Jeh Johnson, the Defense Department’s general counsel, voiced concerns that alterations to the AUMF could inadvertently limit rather than reaffirm the executive power to conduct the battle against terrorist groups. This is a legitimate concern, but it can be addressed through consultation with lawmakers.

Senate action will have to be reconciled with the House version of the bill, which Mr. Obama has rightly threatened to veto. Failure to reach agreement would be an abdication of responsibility to the courts. The country needs a sensible antiterrorism policy to combat an unconventional and unrelenting enemy. The president and lawmakers should be the architects of such a plan.