WHATEVER YOU THINK of Ramsey Clark's mission to Tehran, it would be a great mistake to suppose that he and nine other Americans who attended the conference there had committed "criminal acts" in going in the first place. It is conceivable that the Department of Justice might decide to bring criminal charges against Mr. Clark and the others. And it is even conceivable that a jury might convict them either of breaking the travel ban imposed by President Carter or of engaging in negotiations with a foreign power. But it is unlikely that the Supreme Court would uphold any such convictions. Even this Supreme Court, we like to think, would not find a constitutional basis for such prosecutions.

Mr. Clark was quite right when he said in Paris that American citizens have inherent rights to travel, to assemble and to speak their minds. The limitations government can place on those rights are minimal even in wartime and, at least as of this writing, the American government had not declared war on Iran. In peacetime, the government can discourage travel to particular countries, warn those who go that they will not have the usual protections provided to American citizens while they are there and use other psychological devices to persuade citizens to stay away. But it should not try to prosecute individuals who exercise that inherent right to travel.

Secretary of State Muskie clearly and wisely underscored this distinction when he said on Sunday that the purpose of the travel ban was "not to punish people who violate it, but to prevent people from going." At a simple political, diplomatic level, it would probably be a serious mistake for the government to deviate from that description, since it would run a substantial risk of demonstrating the flimsy legal basis on which President Carter acted when he imposed that ban in the first place a few weeks ago. The argument people wish to conduct with Mr. Clark and his co-conference-goers should be confined to that -- argument. The rest -- the idea of prosecution -- should be junked as the dangerous and bad idea it is.