THE NUCLEAR Regulatory Commission and Common Cause are locked in a dispute that, U.S. District Judge Edward Curran now threatens, could send the five NRC commissioners to jail on contempt-of-court charges.

The issue is whether the NRC may hold private meetings when it makes decisions on the agency's budget. The proper answer to that may seem obvious to you -- but it doesn't to everybody: Common Cause asserts that the Sunshine Act requires that all such meetings be open to the public. The NRC believes, however, that the final sessions in the lengthy series of budget meetings, in which the commissioners make decisions and decide negotiating strategy, fall under an exemption in the act that allows meetings to be closed if opening of the session would "frustrate" the agency's purpose. The NRC commissioners have concluded that one question is important enough to appeal to the Supreme Court, if necessary.

There is much of value in the Sunshine Act, and the opening of more government meetings to public observation has probably thwarted some improper dealings and conflicts of interest in the conduct of public business. But both in theory and in practice the law is badly flawed.It applies, first of all, only to agencies headed by more than one individual, so-called "collegial" agencies. This limitation has no rationale other than its purely political origins. It means that the relatively few affected government agencies are subjected to "sunshine" requirements that would be unthinkable in a Cabinet agency making similar decisions. Imagine the response if a group of taxpayers showed up at, say, the secretary of energy's office with a request to attend the meeting in which the secretary makes final decisions on the department's budget and devises a strategy for dealing with the budget-cutters at the Office of Management and Budget.

The Sunshine Act's authors apparently had little concern for the practical realities of running a government agency, or any other institution. The law forbids meetings of a quorum of an agency's members without prior public notice and a variety of other elaborate requirements. The effect is to shift much of an agency's decision-making from meetings to circulated memos, a practice that accentuates differences by eliminating the give and take of discussion and considerably slows the regulatory process.

There are, moreover, plenty of good reasons to conduct certain business in private, among trusted colleagues. Not many people would want to ask a stupid question, say rude things about others or toss out untested new ideas in front of an audience. Closed meetings do not necessarily imply corruption, conspiracy or general dirty doings.

Perhaps in overreaction to earlier abuses, the NRC has been particularly rigid in adhering to the letter of this law, even as it struggled to handle the unprecedented emergency at Three Mile Island. Not all of this agency's well-known failings can be laid at the act's door, but many are certainly related. To argue, as Common Cause now does, that the commissioners may not even make budget decisions in private is to carry a reasonable goal to an absurd end. Judge Curran, we hope, will think again. After that Congress could profitably reexamine the question of just how much sunshine advances the public interest.