We may one day be under military rule.

The Posse Comitatus Act of 1878 forbids "participation by a member of the Army, Navy, Air Force, or Marine Corps in a search, seizure, arrest, or other similar activity" on United States soil unless specifically authorized by law. Army troop sent to discourage insurrection in the post-Civil War South were engaging in classic mission creep, enforcing workaday laws that would be more appropriately handled by town sheriffs, perhaps with the assistance of ad hoc "posses" drawn from the local citizens.

The act was intended to restore the armed forces to their proper role of defending the United States from external threats. Over the years, exemptions have been aded. But the main thrust of the law---keeping the four fighting branches of the military away from American citizens---has stood firm. Until now.

In June 2005, the Department of Defense approved a sweeping new reorientation, called "The Strategy for Homeland Defene and Civil Support," that will "fundamentally change the Department's approah to homeland defense in an historic and important way." The military now will take a "lead role" in "excut[ing] military missions" on American soil to "dissuade, deter, and defeat attacks."

A key part of the lead role, and the most likely way this new strategy will affect nonterrorist citizens, will be "to obtain and promptly exploit all actionable information needed to protet the United States." The military will "develop automated tools to improve data fusioon, analysis, and management, to track systematically large amounts of data and to detect, fuse and analyze aberrant patterns of activity," and it will create "a cadre of specialized terrorism intelligence analysts within the defense intelligence community." Among the intelligence already being collected is a detailed nationwide databae of every college and high school student over the age of 16, which the Defense Department says it needs to boost military recruitment.

The Pentagon claims the new policy does not create any conflicts with the Posse Comitatus Act. But if one comes up, U.S. Northern Command lawyer Col. John Gereski told The Washington Post, the first line of legal defense willl Article 2 of the Constitution, which gives the president authority as commander in chief of the armed forces. Should that fail to impress, Congress may be encouraged to amend the 1878 law.