A LEGISLATIVE CHARTER for the FBI was unveiled at the Department of Justice last week and promptly attacked from every side. Some old friends of the FBI claim the charter would limit too strictly the bureau's jurisdiction and powers. Some civil libertarians claim it isn't strict enough. This was to be expected, since the charter has been four years in the fashioning and is a collection of compromises on issues about which feelings are strong.

There is, for example, the argument about the FBI's efforts to disrupt or discredit organizations that fall into official disfavor - the COINTELPRO-type tactics employed in the 1960s and early 1970s. What should the charter say about this? Civil libertarians claim it must specifically prohibit the FBI from conducting such operations. Incoming Attorney General Benjamin R. Civiletti replies that these do not need specifically to be prohibited because the FBI dould not engage in them legally without exceeding the authority the charter already gives it.

This may sound picky to you, but it provides an example of the intricate - and important - debate that is likely to get going in Congress this fall concerning the charter's details.One view is that, in light of the disclosures about the FBI's terrible recent history, as little as possible in its future should be left to the exercise of discretion or to casual interpretations of charter terms. The other view is that a charter so tightly drawn would cripple the FBI's legitimate investigative role.

Thus, there will be arguments about how much evidence of criminal conduct the FBI should have before opening on an investigation, how much of a check on its operations should be placed in the courts or Congress and how broad should be its powers to protect informants, demand access to records and so on. Each of these issues is sufficiently complicated to deserve a full airing in public hearings before a judgment is made.

The one point on which almost everyone agrees is that Congress should handle these questions quickly. The FBI needs a charter so that its agents will know precisely what is expected of them and what they are entitled legally to do. The public wants the cloud of suspicion over the FBI's activities to lift. The document produced by the Justice Department is an excellent starting point. It may need some revision, but it puts the right questions before Congress - and in a form that demands they be answered.