This is true, but his reasoning as applied to Flynn is so dubious that it’s become chum for a feeding frenzy among lawyers on Twitter today. Dershowitz’s point is straightforward: It’s only a crime to lie to a federal agent if you lie about a material fact. If the sky is blue and you tell the FBI it’s red, there’s no jail time for that because that fact isn’t material to whatever it is they’re investigating.

But the question of which facts are “material” isn’t always clear cut. How to define them? Well, says Dershowitz, here’s one way: If the feds already know the fact before you mention it, then it can’t be material. Your lie hasn’t misled them. They won’t waste any time or money investigating it. They already know the truth. No harm, no foul, no prison. In fact, if the feds are asking you a question about a fact they already know, presumably they’re only doing it in hopes that you’ll perjure yourself, right? That’s the Flynn situation, Dershowitz argues today in an op-ed.

Flynn, during his brief time as national security adviser to President Trump, told FBI agents untruths that are contradicted by hard evidence. Why he did that remains a mystery because, with his vast experience in intelligence gathering, he must have known that the FBI had hard evidence of the conversations he denied having with a Russian diplomat. Be that as it may, this reality does not automatically exclude the possibility that the FBI acted improperly in eliciting untruths from him.

The FBI knew the truth. They had recordings of the conversations. Then why did they ask him whether he had those conversations? Obviously, not to learn whether he had them but, rather, to give him the opportunity to lie under oath so that they could squeeze him to provide incriminating information against President Trump.

Maybe Flynn didn’t commit a crime — if Dershowitz’s definition of “material” is accurate.

But it isn’t accurate, per various former prosecutors who are mad at Dershowitz for what they consider to be a bit of Fox-friendly chicanery in the clip below. He’s surely aware of what a federal court would regard as “material” or not, but instead of explaining that to Fox viewers he’s substituting his own idea of how he thinks “material” should be defined.

Former prosecutor turned defense attorney Ken White agrees with Dershowitz in principle, that it should be harder for the feds to put someone away for lying to the FBI. But what the law should be and what it is are two different things. Flynn’s lies are material even if the feds already knew the truth:

Pretty clear. To judge whether a fact is material, you look at whether the lie hypothetically could have misled the government, not whether it actually did. An old pro like Dershowitz doubtless knows this; what Mariotti and White suspect is that he’s telling the pro-Trump Fox News viewership what it wants to hear, suggesting without clearly stating that Flynn has been railroaded by the courts. He hasn’t. If, like Dersh, you think the standard for what constitutes a criminal lie about a “material fact” should be higher, that’s a perfectly fair opinion. Emphasis on opinion. Would it be clear to the average person watching this clip that famous law prof Alan Dershowitz is merely giving an opinion?

One other note about Flynn. Mariotti and White, among others, marveled today that he’s going to end up with no jail time despite his business associates being indicted. How much information has Flynn given Mueller, and how valuable must it have been, for him to end up with that kind of sweetheart deal?