Two of the most well-known legal talking heads in cable news went at it on Wednesday evening over President Donald Trump’s continued attacks on the special counsel investigation into the 2016 presidential election.

Jeffrey Toobin clashed with his former Harvard Law School professor Alan Dershowitz, expressing exasperation over the professor emeritus’ continued and unflinching support for Trump’s legal arguments.

During the nine-minute CNN segment, moderated by Anderson Cooper, longtime CNN legal analyst Toobin called out Dershowitz for his public opposition to the appointment of Special Counsel Robert Mueller.

“I don't know what’s going on with you,” Toobin said, getting right to the point.

Moments later, he added: “How has this come about that in every situation over the past year you have been carrying water for Donald Trump? This is not who you used to be, and you are doing this over and over again in situations that are just obviously ripe with conflict of interest and it's just like—what's happened with you?”

Undeterred, Dershowitz pointed out that he attacked the president for issues like the proposed ban on Muslim immigration, and clarified that he broadly opposed special counsel investigations.

“I have been utterly and completely consistent and nonpartisan and Jeffrey, you haven't,” he said.

The two ubiquitous cable-news talking heads have a decades long relationship that has only occasionally led to public conflict. Toobin wrote extensively about Dershowitz’s role on O.J. Simpson’s 1994 legal team, and critiqued the then-defense lawyer’s manipulation of the media.

Dershowitz, a Harvard professor and one of the most high-profile legal experts in America, has repeatedly defended Trump’s legal stances.

With regards to the ongoing Russia investigation, Dershowitz has repeatedly mimed the president’s arguments, declaring Trump had definitively not obstructed justice by firing former FBI director James Comey, and that Trump was allowed to tell Comey to lay off investigating key Trump allies.

The Harvard professor told Toobin he has lost liberal friends and even some weight because of his willingness to advocate on television in Trump’s favor.

Despite Dershowitz’s assertion that he does not carry water for Trump, it seems as though many on the right would agree with Toobin’s assessment of Dershowitz’s Trump-friendly turn.

“I don’t know what has happened to Professor Dershowitz,” right-wing radio host Rush Limbaugh said last year. “But whatever it is, I like it.”