Fox News anchor Chris Wallace took Alan Dershowitz, a member of President Donald Trump’s impeachment defense team, to task over his shifting positions on impeachment over the years, noting on Sunday that the famed attorney previously claimed a president didn’t have to commit a crime to be impeached.

During an interview on Fox News Sunday, Wallace played a clip of Dershowitz discussing President Bill Clinton’s impeachment in 1998 in which Dershowitz argued that “if you have somebody who completely corrupts the office of president and who abuses trust and who poses great danger to our liberty, you don’t need technical crime.”

Considering Dershowitz will now be arguing before the Senate that Trump can’t be impeached because the House’s articles don’t detail a “technical crime,” Wallace confronted the retired Harvard law professor on his apparent flip-flop.

“Let me ask about this, because when you argue that case, that what didn’t have to be a crime in the Clinton impeachment, I find it very hard to believe that you had not studied the only other presidential impeachment in history, which was the [Andrew] Johnson impeachment,” Wallace said. “So suddenly discovering that the key issue is what Justice Curtis argued in 1860, you’re too good a lawyer not to have studied that back in 1998.”

Dershowitz attempted to argue that crime wasn’t an issue in the Clinton impeachment because the then-president was charged with a crime, prompting the Fox host to point out that “we just put the sound bite up where you said it doesn’t have to be a crime.”

“I’ve been immersing myself in dusty old books and I’ve concluded that no, it has to be a crime, it doesn’t have to be a technical crime,” Dershowitz countered. “That’s what scholars do—that’s what academics do.”

The lawyer also highlighted that Democrats and liberals have also changed their stances on impeachment, noting that fellow Harvard alum Laurence Tribe once said a sitting president couldn’t be prosecuted but has since argued the opposite.

“It’s also what lawyers do, which is depending on the facts of the case and the side they’re arguing, they find an argument to make,” Wallace shot back.

Dershowitz, meanwhile, asserted that he had been making his argument “way, way, way before I was given the role to argue the constitutional case” for the Trump team.