IT IS NOT surprising that the Supreme Court ruled against former CIA officer Frank W. Snepp Tuesday. In failing to get clearance from the agency for his book, "Decent Interval," Mr. Snepp broke a contract he had signed when he entered the spy business. Judges don't like broken contracts, and this one, the justices said, not only was clearly enforceable but also required Mr. Snepp to forfeit to the government all the royalties his book produced.

What is surprising is that the justices seemed so overwhelmed by the claim of "national security" made in the case that they disposed of the serious issues it raised in a casual, even cavalier manner. Without listening to one word of argument, the court slapped down Mr. Snepp and then went beyond the confines of his case to give the CIA and, presumably, other national security agencies something approximating total power over the writings of former employees. They even opened up questions, which sooner or later will be explored by some eager agency head, about the right of other government agencies to limit the post-employment writings of employees.

In two footnotes, for example, the justices seemed to say the CIA didn't even need the contract with Mr. Snepp to stop him from writing about the agency after he left it. The "compelling interest" of the government in protecting national security information justifies the imposition of "reasonable restrictions on employee activities," the court said. The language chosen by the justices is so broad that it seems to reach not only books written by CIA agents but books writen by Cabinet officers and other high-level officials who have had access to "confidential sources and materials." Some readings of that language would permit the government to require writers of memoirs -- Henry Kissinger, Arthur Schlesinger -- to submit manuscripts for review.

The court did not rule that the government can stop a former employee -- CIA or other wise -- from publishing unclassified information, which is what Mr. Snepp said he was doing. If Mr. Snepp had submitted his manuscript for review, it explained, any disputes between him and the CIA over what information should not be published would have been decided by courts. But by failing to discuss seriously the First Amendment implications of such a review process, the court opened the possibility that review-by-contact can be imposed in almost any area of government employment. While such a review might not change the content of unclassified manuscripts, it certainly would inhibit criticism.

While we can understand the decision as it applies to Mr. Snepp -- the sensitivity of the CIA's activities and the contract he signed make that situation unique -- the court's general language is far too broad. The "uninhibited character" of its "exercise in lawmaking," as Justice John Paul Stevens described the decision in dissent, cries out for a congressional review of the damage that has been done.