When the Republicans in Congress impeached President Bill Clinton over the Monica Lewinsky affair, they insisted that it wasn't about sex, it was about lying. Of course that wasn't true. Even at the height of their power-mad self-delusions (when Newt Gingrich was conducting his own affair with an aide while prosecuting the president), Republicans realized that to make lying an impeachable offense was opening a door no politician should eagerly walk through.

Of course it was really about sex. Nevertheless, those of us who thought impeachment was an outrageous abuse of power by the Republicans had to accept that Clinton had, clearly, lied. And our argument was this: Clinton made a mistake. He should not have lied. But he lied in answer to questions he should not have been asked. He should not have been put in a position where he had to choose: He could lie under oath, and be impeached or worse, or he could tell the truth, and embarrass himself and his family, and probably still be impeached or worse.

In short, he was caught in a "perjury trap." Bill Clinton chose wrong — it all came out anyway — and he defeated impeachment, though you wouldn't say he got away scot-free.

On Tuesday, President Bush commuted the sentence of I. Lewis Libby Jr., Vice President Dick Cheney's former chief of staff, who was convicted of lying to investigators about the CIA leak case. Libby will escape prison, but he won't get away scot-free, either. He faces a fine of $250,000 and two years of probation, and if he was thinking of cashing in big on K Street like so many of his administration colleagues, he had better think again.

Libby's critics are not the people who criticized Clinton. And his defenders are not Clinton's defenders. But the scripts are similar. The Libbyites believe that their man is being railroaded and shouldn't have been prosecuted, let alone convicted, for his involvement in a campaign of leaks intended to discredit a critic of the administration, former Ambassador Joseph Wilson. Libby's critics respond that this isn't about leaking, it's about lying.

But of course, this really is about leaking. It's the nefarious, though inept, campaign to sully Wilson that outrages critics of the administration. True, Libby was not the source for Robert Novak, whose column identifying Wilson's wife as a CIA operative started the whole business. And Libby's most prominent leakee, Judith Miller, the former New York Times reporter who went to jail rather than reveal a source, didn't actually write about the case. But Libby was part of the cabal that was conspiring to discredit Wilson and, more generally, to convince people that Iraq was strewn with nuclear weapons.

So when Libby was questioned by federal investigators pursuing the leaks, he, too, was caught in a perjury trap. He could either tell the truth, thereby implicating colleagues and very possibly himself, in leaking classified security information (the identity of Wilson's wife), or he could lie. In either case, he would be breaking the law or admitting to having done so, and in either case, he could have gone to prison. Libby, like Clinton, made the wrong choice.

There is nothing wrong with a perjury trap, as long as both sides of the pincer are legitimate. The abuse comes when prosecutors induce a crime (lying under oath) by exploiting an action that is not a crime. The law about "outing" CIA operatives is apparently vague enough that it isn't clear whether Libby violated it.

But let's leave that aside. Exposing one of your country's intelligence officers is a bad thing to do. If it isn't against the law, it ought to be, right? Well, this is where the press comes in. At first, many in the press supported appointing a special prosecutor to investigate.

The crime, if there was one, was leaking government secrets to journalists. If you were investigating that crime, where would you start? Yes, of course, by questioning journalists. The government leakers, if you found them, would be protected by the Fifth Amendment. You would need more and different evidence, and only journalists had it.

The special prosecutor, Patrick Fitzgerald, followed this common sense logic straight into a First Amendment buzz saw. News organizations that insisted on the need to get to the bottom of the leak also insisted that no journalist should have to supply information to this investigation.

The leaks that The Times and other papers defended so ardently were not laboratory examples of press freedom at work. Quite the opposite: They were part of the nefarious campaign by the vice president's office to discredit Wilson — itself part of the larger plot to convince the world that there were weapons of mass destruction in Iraq, which was, of course, part of the plot to get us into the war in the first place. And it worked.

It takes two to leak. How can it be fair that one party to the leak doesn't even have to testify about it, because leaks are so vital to the First Amendment, while the other party might go to prison for it? And if that is unfair, how is a perjury trap fair when it forces a leaker to choose between going to prison for the leak and going to prison for lying?

So as much as I dislike the war in Iraq, as much as I dislike Bush, as much as I expect that I would dislike Libby if I ever met him, I feel that he should not have had to face a perjury trap: the choice between prison for lying, or prison for his role in a set of transactions that the press regards as not merely OK but sacrosanct.

In fact, if journalists had a more reasonable view about this, the reporters whom Libby tried to peddle this story to would have said, "Look, outing CIA agents is bad, and we are not going to help you do it anonymously." I bet that today, commuted sentence and all, Libby wishes they had done just that.

Libby was caught in the same perjury trap that snagged Clinton in Lewinsky affair

Michael Kinsley is a columnist for Time magazine. He wrote this commentary for The New York Times.