THE MOST INTERESTING aspect of the recent news "leak" at the Supreme Court is not its content but the fact that it happened at all. There is no suggestion of anything improper, other than that ancient custom has been violated. The loose talking should have no impact whatever on the outcome of the case involved. But the departure from "good form" does suggest that all is not well inside the marble palace where the Justices work.

The leak, in case you missed it, was to the effect that the Justices have voted, 5 to 3, to refuse to review the convictions of three major Watergate figures, that the Justices who voted to hear the case were all nominees of President Nixon (Chief Justice Burger and Justices Blackmun and Powell), and that the Chief Justice held up announcement of that result in the hope of persuading one of the five to change his mind.

Assuming all this is true, we think it is unfair to imply - as some news stories have done - that the justices on either side of issue voted and acted as they did for political rather than legal reasons. It is not surprising to find Messrs. Burger, Blackmun and Powell voting together. They frequently do. And it is not surprising, at least to us, that they would vote to hear this particular case, given the general views they seem to have on the kinds of legal issues involved. Nor would it have been particularly startling or portentous for the Chief Justice to have held up the announcement of the vote for a week: Members of the Court frequently (and properly) try to influence their colleagues.

But it is unusual, to say the least, for information of this kind to leak out of the Court's deliberations. The Justices have taken great pains through the years to keep their work secret until they are ready to make it public. When leaks do occur, they are usually the result of some internal squabble or basic disagreement among the Justices that may not even be relevant to the matter at hand. In other words, this leak may have far more to do with something that is going on inside the Court - the way it is being administered, for example - than it has to do with this Watergate case.

The Court, in any event, is likely to ignore the whole episode - at least officially. It has refused, rightly, it seems to us, to let the lawyers for the Watergate defendants argue that the episode might affect the outcome of the case. We doubt that it will have any effect and we are sure that even if it does, the Court is not going to admit it, if only because judicial integrity rests on the belief that extraneous factors like leaks do not affect judicial decisions. So public knowledge of what precisely is involved will have to wait for further leaks - or the writing of history.