IN ASSERTING executive privilege to shield from Congress deliberations over his grant of clemency to a group of Puerto Rican terrorists, President Clinton is once again courting a public relations disaster. This time, however, Mr. Clinton is right. Unlike some of his previous invocations of the privilege, this one concerns a core executive branch decision. The communications he seeks to protect relate unambiguously to an affair of state on which the president must be entitled to the confidential advice of members of the executive branch. They also concern an area -- the power to grant pardons and clemency -- over which Congress has no authority whatever and, therefore, only the most muted of oversight interests. If executive privilege does not cover the Puerto Rico flap, it does not meaningfully exist.

The notion of executive privilege as a nefarious power stems principally from its abuse during Watergate. The disrepute the privilege has since suffered is understandable, and we -- as a newspaper -- harbor a certain suspicion of any privilege intended to keep government material away from public view. But too dogmatic an opposition to executive privilege can also obscure the important role that presidential confidentiality can play in ensuring that presidents receive candid advice. Particularly when, as here, the president is wielding a power that is by constitutional design unreviewable by any other branch of government, the argument for a strong privilege is good. This is not an argument for secrecy; we would, after all, welcome any information about this process. It is, however, an argument against a congressional power to compel disclosure.

Acknowledging the validity of the privilege in situations such as this one carries little danger of creating a wall behind which presidents can shield their malfeasance. Where actual corruption is being investigated -- if, for example, a president were accused of selling pardons -- executive privilege would yield to the needs of a grand jury. Moreover, the president cannot use the privilege to hide material that is not clearly germane to a constitutional function of his office. Where Congress is investigating a matter over which its oversight power is clearer, the argument for a robust privilege is also weaker than it is in this case.

But the core of executive privilege is the idea that the president must be able to obtain useful advice to carry out his constitutional role. If Mr. Clinton is willing to take the political heat for keeping this material from Congress, he should be entitled to do so.