HOUSE AND SENATE negotiators have improved legislation governing the handling of terrorism suspects — but not enough.

The provisions, contained in the 2012 National Defense Authorization Act, regulate everything from capture to release. They no longer contain some of the most odious measures contained in earlier drafts. Those would have required military detention for both foreign nationals and U.S. citizens suspected of terrorism activities. They flirted with barring terrorism prosecutions in civilian courts. They virtually tied the hands of the defense secretary in repatriating or transferring detainees to third countries in the absence of a court order.

These ideas have been scuttled, but their replacements — while less extreme — are still unnecessary and unwise.

The new approach is designed to limit military detention to foreign al-Qaeda operatives and permits federal courts as a venue for terrorism trials. It allows the president and defense secretary to waive certain requirements in the interest of national security. The revamp, in other words, leaves some room for the executive branch and its law enforcement components to maneuver.

Flexibility is preferable to flat and often unworkable directives, but in this case it also raises questions about why lawmakers insist on codifying these provisions when they have made it relatively easy for the executive to disregard them. In trying to respond to administration concerns, lawmakers have watered down language and introduced confusion in the form of directives that threaten to bollix up law enforcement and military personnel when they most need to be decisive. Congress also would inexcusably prevent the Defense Department from bringing detainees currently at the U.S. naval base at Guantanamo Bay, Cuba, into the country and from adapting U.S. facilities to hold these detainees.

Almost from the start of the Obama administration, lawmakers, led by conservatives, have unjustifiably circumscribed presidential authority on many terrorism-related issues. Also from the beginning, President Obama has not fought these congressional incursions with sufficient vigor. Now Congress is once again overstepping its bounds as it attempts to micromanage the president in battlefield and law enforcement operations. Mr. Obama finds himself in an unenviable position because the measures are included in a defense bill, likely to be voted on this week, that includes provisions dealing with military pay and other important issues. But the muddled detainee measures certainly are veto-worthy.