THE LATE SAM RAYBURN used to say that the three most important words in the English language were "just a minute." We wouldn't agree more: just a minute -- everyone in America within shouting range of a TV or newspaper may now "know" that a bunch of legislators were caught in corrupt acts by an FBI-- "sting" investigation. But in fact, we "know" nothing. Crimes may have been committed, as the stories assert they were, but there have not yet even been any charges, let alone any indictments, let alone any convictions. Even members of Congress, if we may say so, deserve to be presumed innocent until proved guilty. And although the tale, as it has unfolded so far, has some pretty unsavory aspects to it, not all of those concern the activities in which the legislators are said to have engaged.

Take the story of Sen. Larry Pressler, described by one of those anonymous law-enforcement "sources" as "an honorable man." Pressler said he got a message about a possible campaign contribution, was taken to a house on W Street, and talked to about introducing private immigration bills. When he failed to bite, even though the magic number of $50,000 was mentioned, and went away empty-handed, one of those who took him there said he had blown it.

If that is the whole story -- and the "if" is an important one -- something is plenty wrong. It sounds as if the FBI had not only been creating the atmosphere in which a crime could be committed, but had also fabricated the crime itself down to the last detail -- and then tempted a member of Congress to commit it. Leaving aside the legal technicalities of defining "entrapment," no citizen -- member of Congress or not -- should be required to prove his integrity by resisting temptation.

There is a substantial difference between the first "sting" operation and this one. In the original, the police set themselves up as buyers of stolen goods and waited for the thieves to bring in the loot. In this one, as best we can make out from the torrential "leaks" that have occurred, the FBI created its trap without having received evidence that some prior crime had been committed.

Assurances, of course, are now being offered by the Department of Justice and the FBI that this investigation was carefully monitored and that nothing was done that violates judicially approved law-enforcement techniques and so forth. That may well be so, given the broad sweep of deceptive activities by law-enforcement personnel that the courts have approved. But not everything that is legal is right.

It cannot be right to set people up in this way and then let it be known that you have film of them committing criminal acts -- before you have so much as warned them or brought criminal charges. That's why it is essential to step back from the current news stories before passing judgment on what is being reported. We, at least, are going to wait until we know a good deal more than we now do about the facts and the investigative deviced used, not to mention the remarkable appearance of network television cameras in front of one legislator's house hours before he was told he was under investigation.