IN seeking to arm the federal government with new powers to combat home-grown terrorism, President Clinton is setting off alarm bells over a cherished democratic tenet: keeping the military out of domestic law enforcement.
As part of his package of antiterrorism measures triggered by last month's Oklahoma City bombing, Mr. Clinton is courting controversy because he wants to add a new provision to a federal law that would allow the military to participate in investigations of domestic terorrism cases involving chemical or biological weapons.
A previous revision to so-called Posse Comitatus Act of 1878, which tightly regulates the circumstances under which the military may be used in domestic law enforcement, authorizes the Defense Department to join in the investigation of nuclear terrorism cases. Other revisions permit the military to provide technical expertise to federal authorities, including radar tracking of shipments of illegal drugs into the United States.
Despite the limited nature of the administration's new proposal, the idea of giving more domestic law enforcement power to the military is rekindling fears about potential abuse that echo a debate ignited by George Washington when he put down Pennsylvania's Whiskey Rebellion tax revolt with federal troops in 1794.
''The fear of the use of the military against American citizens to enforce federal law has been very controversial throughout history,'' notes John Chambers of Rutgers University, in New Brunswick, N.J., an expert on the military's involvement with US civil authorities.
''Civil supremacy over the military is a basic American tradition,'' says Professor Chambers. ''It is hallowed because it comports with individual liberty and the constraints on government. But, it is also hallowed because it has been violated at times.''
The most flagrant abuses occurred in the 1960s and 1970s, when the military infiltrated radical anti-Vietnam War groups and compiled dossiers on thousands of civilians. The fear of such abuse now finds resonance in the antigovernment citizen militias and activists across the political spectrum.
Says Louis Bograd of the American Civil Liberties Union: ''Countries where the military serves in civilian police enforcement have traditionally had the most repressive regimes in the world.''
Lawrence Korb, a former assistant defense secretary who is now at the Brookings Institution, a Washington think-tank, says he opposes the administration plan as the military is already ''treading a fine line because people have been interpreting the regulations broadly.''
Mr. Korb says that he used to deny requests from law enforcement agencies for the military's help ''particularly in the drug area. They wanted more than just information. They wanted us to get involved in apprehensions.''
Administration officials appear acutely aware of the delicate political ground on which they are treading. They stress that their proposal will still tightly limit the circumstances in which the military can be used in domestic law enforcement.
''No one wants the military involved in law enforcement; not law enforcement and not the military,'' Deputy Attorney General Jamie Gorlick told a congressional hearing last week. ''But, where they have the expertise as they do with respect to nuclear, chemical, and biological weapons, we need limited help from them.''
The administration's precise language for revising the Posse Comitatus Act is still being worked on. A first draft of the antiterrorism package sent to Capitol Hill last week contained a blank space where the proposal was supposed to be, congressional aides say.
Some experts question why new legislation is even needed. They point out that the Pentagon already gives technical assistance to federal law agencies. It reportedly provided such help to the FBI during the April 1993 siege of the Branch Davidian compound in Waco, Texas.
Sen. Arlen Specter (R) of Pennsylvania, a former prosecutor who sits on the Senate Judiciary Committee, says he is willing to listen to the administration's arguments, but adds: ''I think you have to limit very sharply military operation in law enforcement.''
Members of both parties, especially majority Republicans, are unhappy with the measure for other reasons, congressional aides say. They do not understand the ways in which the military could help domestic terrorism cases and they are already angered by what they regard as the Clinton administration's over-use of the armed forces for costly nontraditional functions.
The American antipathy toward military involvement stems from the use of troops by the British colonial authorities, Chambers says.
But after the Whiskey Rebellion in 1794, the US Army was used to track down and return escaped black slaves to Southern plantation owners. Immediately after the Civil War, Southern GOP officials used the Army to suppress a campaign of terror led by the Ku Klux Klan and enforce laws granting civil and political rights to former black slaves. The effort failed and in 1877 federal troops were withdrawn from the South. The following year, the Posse Comitatus Act was passed when Southern Democrats in Congress found common cause with Northern lawmakers upset by use of troops to suppress labor strikes.