The concern that many, including this page, expressed about the authorization is coming true: that it could become the basis for a perpetual, ever-expanding war that undermined the traditional constraints on government power. The result is an unintelligible policy without express limits or protective walls.

Last Wednesday, Attorney General Eric Holder said the president would soon shed more light on his “targeted killing” policy. Mr. Obama needs to. In the last few weeks, confusion over these issues has been vividly on display. On one hand, the administration has said it would use lethal force only when capturing a terrorist was impossible, and it did arrest Sulaiman Abu Ghaith, a son-in-law of Osama bin Laden who once served as a spokesman for Al Qaeda, and arraigned him on Friday in federal court in Manhattan. The Washington Post reported last week that counterterrorism officials considered using the authorization law as the basis for the government’s authority to kill Mokhtar Belmokhtar, a militant leader in Algeria and Mali, but decided it did not apply because he was not part of Al Qaeda or an associated group.

But the administration still has not fully disclosed to Congress the legal documents on which the targeted killing program is based. And in that same article, The Post said the administration was debating whether it could stretch the law to make it apply to groups that had no connection, or only slight ones, to Al Qaeda and the 9/11 attacks.

A big part of the problem is that the authorization to use military force is too vague. It gives the president the power to attack “nations, organizations or persons he determines planned, authorized, committed or aided the terrorist attacks that occurred on Sept. 11, 2001, or harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States by such nations, organizations or persons.”

Making the law more specific, however, would only further enshrine the notion of a war without end. And, as Jeh Johnson, then counsel to the defense secretary, said in a speech last November, “War must be regarded as a finite, extraordinary and unnatural state of affairs.”