IT is said that Hunter S. Thompson held a celebration the night J. Edgar Hoover died in the early '70's. Others joined Thompson in their condemnation of Hoover's unwarranted investigations, which included the harassment of Viet Nam protesters, civil rights activists--including Martin Luther King, whose phones were tapped for years--and anyone else with the wrong politics.

It seems that the FBI is up to its old tricks again. The same forms of political harassment and unnecessary investigations that characterized the bureau's activities in the sixties have re-appeared. This month a New York group of lawyers known as the Center for Constitutional Rights obtained FBI files under the Freedom of Information Act--files that document an exhaustive six-year surveillance of hundreds of organizations. All of these political groups had expressed opposition to the Reagan administration's Central American policies. None of them were ever found to be involved in anything illegal.

The original target of the FBI was the Committee in Solidarity with the People of El Salvador (CISPES), a Washington-based group that protests the continuation of war in Central America and raises money for humanitarian aid. Although the FBI suspected that CISPES was giving illegal military aid to leftist guerillas in El Salvador, no evidence was found. So the FBI decided to expand their investigation.

It makes sense. If you can't prove that a group is doing something you suspect, then they must be hiding something. At least, this seemed to be the FBI's rationale. The declassified files show that the FBI even decided to investigate any opposition group even remotely interested in Central America. They checked out the Maryknoll sisters--a Catholic nuns' charity group which aids war refugees. the National Education Association--a non-political teacher's organization, and even the United Auto Workers.

Although the FBI contends that their actions fell within the law, there is a strong possibility that they illegally used wiretaps, infiltration, and other such techniques without probable cause. But the FBI maintains that they were operating under guidelines which permitted the surveillance of groups suspected of terrorist activity.

However this appears to be nothing more than a meager attempt to justify some very disturbing activities. There was no evidence available at the FBI project's beginning that even hinted at actual terrorist activity, let alone any violation of federal law. Indeed, the investigation proved there was none. Nevertheless, the investigations both continued and expanded.

THE only charge any of the hundreds of organizations and thousands of people watched by the bureau are guilty of is their disagreement with U.S. policy in Central America. Though some people would like to think so, this is no crime, just as protesting the Viet Nam war was no crime.

President Reagan's decision to conduct an inquiry into the FBI's conduct shows there was no tangible purpose or justification for the extensive surveillance. Paranoia about communism, not national security, seems to be the motive behind the FBI's actions. Just last September, the FBI asked libraries to lookout for "diplomats of countries hostile to the U.S., particularly the Soviet Union." Fortunately, most librarians found the request to be a ludicrous and flagrant violation of the right to privacy and flatly refused to cooperate. As the director of the New York Library Association asked, "Does anyone with an accent come under suspicion?"

Both investigations, begun and supervised by then-Director of the FBI William H. Webster, smack frighteningly of the McCarthy-era Red Scares. Webster is now the director of the CIA. If he continues to exhibit such paranoia as these two instances show, the CIA could well become an even worse violator of civil liberties and human rights than it has been in the past. Webster may even begin to turn the CIA's covert efforts to home territory, continuing the work the FBI started. Clearly he is a man that must be watched, and it is a sign of hope that even President Reagan has realized this by ordering an investigation.

Webster's successor at the FBI, former Federal Judge William S. Sessions, simply inherited these investigations from Webster and cannot be held responsible. Nonetheless, he must be careful not to engage in such intrusive, unconscionable activities. For their part, the American people must be careful not to allow another Hoover to gain the power to restrict their freedoms. The FBI is a public organization designed to protect the American people, not a secretive KGB designed to protect the government.