Washington ? President Bush signed into law Friday the broadest reorganization of the nation’s intelligence community in more than half a century, overhauling a sprawling system that failed to head off devastating terrorist attacks three years ago and then misjudged the threat posed by Iraq a year later.

The new law, which grew out of this summer’s report by the national commission that investigated the Sept. 11, 2001, strikes on the World Trade Center and the Pentagon, erects a new architecture for U.S. intelligence gathering designed to end the bureaucratic infighting and miscommunication that preceded the attacks.

Under the new system, the 15 separate intelligence agencies will be brought together under a single command structure headed by a director who will control most of their budgets and report to the president. The measure creates a national counterterrorism center, bolsters border and aviation security, and establishes a civil liberties board to serve as a check on excesses in the fight against terrorism. And it will change such things as the way Americans get driver’s licenses and the way foreigners get visas.

Bush, who initially opposed creation of the 9-11 commission and later resisted some of its recommendations, hailed the resulting legislation Friday as a historic step toward heading off future terrorist attacks.

“A key lesson of September the 11th, 2001, is that America’s intelligence agencies must work together as a single, unified enterprise,” he said at a ceremony at the Andrew W. Mellon Auditorium, the same hall where President Harry S. Truman signed the treaty creating NATO in 1949.

The president gave no indication whom he might pick to fill the new position of director of national intelligence. Bush faces the challenge of finding someone with “extensive national security expertise,” as required by the law. The measure indicates that Congress wanted either the director or his principal deputy to be an active or retired military officer.

Among the names floated are retired Gen. Tommy Franks, who commanded troops in Afghanistan and Iraq; Adm. William Studeman, a former deputy CIA director now serving on a Bush panel studying the intelligence failures on Iraqi weapons programs; Lt. Gen. Michael Hayden, head of the National Security Agency, which handles electronic eavesdropping; Frances Fragos Townsend, the president’s homeland security adviser; and Richard Armitage, outgoing deputy secretary of state.