Liberal law professor Alan Dershowitz continued his defense of President Donald Trump on Sunday.

“You cannot question a president’s motives when the president acts,” he said on This Week. “If a president pardons, that’s it. If a president fires, that’s it. You can’t go beyond the act and get into his motive or into his intent.”

Host George Stephanopoulos had asked if Special Counsel Robert Mueller could make a case that Trump committed obstruction of justice. Dershowitz said no, because a president can’t be charged for obstruction for “merely exercising his power” under Article II of the U.S. Constitution.

Stephanopoulos pressed him on a president’s motive. For example, if a POTUS pardoned someone to cover up a murder. Dershowitz dismissed that.

“It doesn’t matter,” he said. “The pardon is the pardon. The covering up of the murder may be an independent crime. The pardon cannot be the actus reus of a crime because you cannot have an actus reus of a crime that is a constitutionally protected act.”

Mueller is leading an investigation into possible collusion between Russia and the Trump campaign during the 2016 election. The president has repeatedly called the probe a “witch hunt” by Democrats. Before he was fired as FBI Director, James Comey was leading the investigation, and some say Trump committed obstruction of justice by firing Comey in the middle of the probe.

[Screengrab via ABC News]