Using military to 维持秩序 is illegal. Here is an article.

America dips its toes in the Rubicon

Federal officials say that the government's hands are tied when it comes to protecting Americans from terrorists striking within our borders -- and that the culprit is an archaic 19th century statute that prohibits military personnel from enforcing the law. Homeland Security chief Tom Ridge claims that while it "goes against our instincts as a country to empower the military with the ability to arrest," the 1878 Posse Comitatus Act, which restricts the domestic role of federal troops, should be reconsidered.

That sounds pretty serious. We certainly don't want to hobble our country's ability to defend us. But why does it go against our instincts to use troops as police? And where did this Posse Comitatus Act come from?

At the founding of the United States, standing armies were viewed with considerable fear. The now almost-forgotten Third Amendment to the Constitution was inspired by the abusive treatment of civilians by British troops. Steeped in classical traditions, the founders also drew upon the experience of the Roman Republic, which forbid its generals to bring their forces back across the Rubicon River toward Rome -- a prohibition defied by Julius Caesar, leading to the establishment of a centuries-long dictatorship.

After the Civil War, northern troops occupied the defeated states of the South amidst reports of abusive treatment of civilians and great resentment. In the presidential election of 1876, the army guarded polling places, fueling suspicions that the disputed victory was stolen for Rutherford B. Hayes -- and spurring the passage of the Posse Comitatus Act.

The original wording of the law states quite simply:

Whoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or the Air Force as a posse comitatus or otherwise to execute the laws shall be fined under this title or imprisoned not more than two years, or both.
The Posse Comitatus Act has served more as a general principle than as a firm barrier against the domestic use of the military. In recent years, it's been weakened, notably by amendments allowing the use of the military to enforce drug prohibition laws.

Virtually every use of troops at home despite the law has worked to demonstrate the wisdom of the original restriction. The 1932 deployment of soldiers under General Douglas MacArthur against "Bonus Army" marchers in Washington, D.C. was one such incident. It resulted in the death of at least one of the World War I veterans among the protesters and a multitude of injuries as MacArthur refused orders to exercise restraint.

Just within the past few years, a Marine assigned to stop drug smuggling across the Mexican border killed a teenager herding his family's goats.

As Timothy Edgar, a counsel for the ACLU notes, "The military's mission is not to respect constitutional liberties. Its mission is to use overwhelming force to defeat and kill the enemy."

The Cato Institute's Diane Cecilia Weber agrees, warning, "Confusing the police function with the military function can lead to dangerous and unintended consequences -- such as unnecessary shootings and killings."

In fact, Weber's cautionary words came several years ago, in a paper documenting the problems that have arisen since many police departments began receiving military training and equipment as part of federal efforts to restrict the flow of drugs. Reports of abuses of civil rights and uses of excessive force flow from communities where police have been taught to treat the areas in which they live as occupied territory.

Can soldiers living in barracks be expected to exercise greater restraint than police officers who return home at night?

Perhaps more familiar with the power at their command, many Pentagon officials oppose any further loosening of the Posse Comitatus Act's restrictions. Defense Secretary Donald H. Rumsfeld and Gen. Richard Myers, chairman of the Joint Chiefs of Staff, are already on record as opposing any such talk.

But at least a few politicians agree with Tom Ridge that unleashing the military at home is a fine idea. Senate Republican Whip Donald Nickles wants the law changed, "maybe to the point of also giving our military some police powers." Democratic Senator Joe Biden also says that the law "has to be amended" to expand the military's role.

Of course powerful politicians may believe that they're immune to the excessive use of force and abuses of due process that seem to come hand in hand with putting troops in the streets. But soldiers deployed to solve troubles at home have a history of deciding that the politicians who command them are part of the problem. Matthew Carlton Hammond addressed that issue in a 1997 paper for the Washington University Law Quarterly in which he urged tighter adherence to the principles of the Posse Comitatus Act. After reviewing the historical use of troops in the U.S., he warned: "Increasing the involvement of the military in civilian law enforcement will make it difficult to maintain the military's subordinate role over the long-term."

That's a concern that was millennia old when George Washington and Thomas Jefferson discussed Caesar's crossing the Rubicon. If today's politicians don't care about the risks posed to civilians by using soldiers as police, they may at least want to consider the firmness of their own grasp on the reins of power.