FIRST, LET'S TAKE the case of Andrew Young, a useful public servant who, once again, has used the special license of the president's personal regard for him to embarrass his chief. Ambassador Young chose the moment when the U.S. government was trying to influence the Kremlin's treatment of several dissidents to declare that there are "hundreds, maybe even thousands of people I would call political prisoners in U.S. jails." A more effective way to undercut the president's concern could scarcely have been imagined. As usual, Mr. Young later elaborated. But by failing to bring out the basic point that, in stark contrast to the Soviet Union, the United States has a legal and political system intended to protect against such over-reachings by the state - or at least to remedy them if they occur - he compounded the original offense.

It is probably vain to expect Mr. Young to impose the normal self-discipline expected of public officials. He will no doubt continue to call his own seriousness into question, to make his nominal superior (the secretary of state) look foolish, and to cheat the president of the respect a subordinate owes the chief executive - as long as Mr. Carter allows him to go on playing teacher's pet. Impeachment is not the remedy. Discipline is.

Our deeper complaint, however, is about Jimmy Carter. On Wednesday, Mr. Carter made his own statement on the trials of Anatoly Scharansky and Alexander Ginzburg. Keep in mind that part of the Soviet campaign against these men has turned on a determination to deter Jimmy Carter's interventions in the Soviet dissident scene by punishing the people he means to help. Keep in mind, too, that American diplomats had been quietly conveying to Moscow that to limit the damage to Soviet-American relations it would be best to steer the trials away from Mr. Carter personally. So right in the middle of the trials Mr. Carter makes a fresh public intervention for Mr. Scharansky and Mr. Ginzburg, repeating his denial that Mr. Scharansky (accused to CIA connections) had CIA connections and condemning anew the process of the trials.

No doubt Mr. Carter feels compassion for the defendants - what decent people do not? Perhaps he also feels that his direct challenge to the Soviets on human rights make him in some indirect way responsible for the example the Soviets seem to be making of these particular defendants. Nor would it be surprising if he were of a mind to preempt charges from the right of insufficient public ardor in the cause. Yet, considerations like these may not fully explain the obsessed and crusading quality of his latest remarks, and certainly they do not justify the timing.

It is not merely that Mr. Carter does not discipline his United Nations ambassador. He does not discipline himself. He conveys the impression that his noble purpose relieves him of worrying about the effects of what he says. This raises anxieties that extend beyond the trials. Nations cannot address each other as though only the matter of personal sincerity were at stake. The personal words of leaders inevitably carry heavy political freight. How is it possible that this ancient truism isnot self-evident to Jimmy Carter a year and a half into his presidency?