John Kennedy

Sen. John Kennedy, R-La. (AP Photo/J. Scott Applewhite)

U.S. Sen. Bill Cassidy, a doctor, has sought to distinguish himself in Congress by focusing on medical issues. So it's probably fitting that his lawyer colleague, U.S. Sen. John Kennedy, is building himself a reputation on legal matters.

While he's generally a strong supporter of President Donald Trump, the freshman Republican is emerging as a tough questioner of the administration's nominees for judicial posts, and of the White House office in charge of them. For months now, Kennedy has used his seat on the Judiciary Committee to highlight some candidates' weaknesses or bad past behavior, even as he's mostly voted the party line in favor of these potential judges.

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But he's taken things up a notch recently by actually casting the first Republican "no" vote against a nominee for the appeals court in Washington, DC. He also withheld — and then granted — support for a nominee to sit on the appeals court in New Orleans, successfully led the charge to derail an epically problematic district court nominee from Alabama, and openly criticized White House Counsel Don McGhan.

This week, in a five-minute interview that has rocketed around the internet, Kennedy destroyed a nominee for a judgeship in Washington, Federal Election Commissioner Matthew Spencer Peterson. Actually, he let Peterson destroy himself by leading him through a series of questions that exposed a shocking lack of both relevant experience and basic knowledge of what happens in federal court.

Whether Kennedy will follow through with more "no" votes remains to be seen, but his work this week led to a rare moment of bipartisan praise. One of Kennedy's Democratic colleagues, Rhode Island's Sheldon Whitehouse, sent the video of the spectacular exchange out on Twitter.

"MUST WATCH," wrote Whitehouse, a former U.S. Attorney. "Republican @SenJohnKennedy asks one of @realDonaldTrump’s US District Judge nominees basic questions of law & he can’t answer a single one. Hoo-boy."

Can't see video below? Click here

Follow Stephanie Grace on Twitter, @stephgracela.