There are lies and there are memory lapses. Bill Clinton denied under oath having sex with Monica Lewinsky. Unless you're Wilt Chamberlain, sex is not the kind of thing that you forget easily. Sandy Berger denied stuffing classified documents in his pants, an act not quite as elaborate as sex, but still involving a lot of muscle memory, and unlikely to have been honestly forgotten.

Scooter Libby has just been convicted for four felonies that could theoretically give him 25 years in jail for ... what? Misstating when he first heard a certain piece of information, namely the identity of Joe Wilson's wife.

Think about that. Can you remember when was the first time you heard the name Joe Wilson or Valerie Plame? OK, so it is not a preoccupation of yours. But it was a preoccupation of many Washington journalists and government officials called to testify at the Libby trial, and their memories were all over the lot. Former presidential press secretary Ari Fleischer testified under oath that he had not told Washington Post reporter Walter Pincus about Mrs. Wilson. Pincus testified under oath that Fleischer definitely had.

Obviously, one is not telling the truth. But there is no reason to believe that either one is deliberately lying. Pincus and Fleischer are as fallible as any of us. They spend their days receiving and giving information. They can't possibly be expected to remember not only every piece, but precisely when they received every piece.

Should Scooter Libby? He was famously multitasking a large number of national security and domestic issues, receiving hundreds of pieces of information every day from dozens of sources. Yet special prosecutor Patrick Fitzgerald chose to make Libby's misstatements about the timing of the receipt of one piece of information — Mrs. Wilson's identity — the great white whale of his multimillion-dollar prosecutorial juggernaut.

Why? Because on his essential charge as special prosecutor — find and punish who had leaked Valerie Plame's name — he had nothing. No conspiracy, no felony, no crime, not even the claim that she was a covert agent covered by the nondisclosure law. Fitzgerald knew the leaker from the very beginning. It was not Libby, but Richard Armitage. He also knew that the "leak" by the State Department's No. 2 official — a fierce bureaucratic opponent of the White House and especially the vice president's office — was an innocent offhand disclosure made to explain how the CIA had improbably chosen Wilson for a WMD mission. (He was recommended by his CIA wife.)

Everyone agrees that Fitzgerald's perjury case against Libby hung on the testimony of NBC's Tim Russert. Libby said that he heard about Plame from Russert. Russert said he had never discussed it. The jury members who have spoken said they believed Russert.

And why should they not? Russert is a perfectly honest man who would not lie. He was undoubtedly giving his best recollection.

But he is not the pope. Given that so many journalists and administration figures were shown to have extremely fallible memories, is it possible that Russert's memory could have been faulty?

I have no idea. But we do know that Russert once denied calling up a Buffalo News reporter to complain about a story. Russert later apologized for the error when he was shown the evidence of a call he had genuinely and completely forgotten.

There is a second instance of Russert innocently misremembering. He stated under oath that he did not know that one may not be accompanied by a lawyer to a grand jury hearing. This fact, in and of itself, is irrelevant to the case, except that, as former prosecutor Victoria Toensing points out, the defense had tapes showing Russert saying on television three times that lawyers are barred from grand jury proceedings.

This demonstration of Russert's fallibility was never shown to the jury. The judge did not allow it. He was upset with the defense because it would not put Libby on the stand — his perfect Fifth Amendment right — after hinting in the opening statement that it might. He therefore denied the defense a straightforward demonstration of the fallibility of the witness whose testimony was most decisive.

Toensing thinks this might be the basis for overturning the verdict upon appeal. I hope so. This is a case that never should have been brought, originating in the scandal that never was, in search of a crime — violation of the Intelligence Identities Protection Act — that even the prosecutor never alleged. That's the basis for a presidential pardon. It should have been granted long before this egregious case came to trial. It should be granted now without any further delay.

Charles Krauthammer is with the Washington Post Writers Group. Reach him at letters@charleskrauthammer.com.