Fox News senior judicial analyst Andrew Napolitano Andrew Peter NapolitanoFox's Napolitano says grand jury erred in Taylor case: 'I would have indicted all three of them' Fox's Napolitano: Supreme Court confirmation hearings will be 'World War III of political battles' Fox's Napolitano: 2000 election will look like 'child's play' compared to 2020 legal battles MORE called the decision by Democrats on the House Judiciary Committee to have former Nixon White House counsel John Dean testify "indefensible."

Napolitano added the move would backfire on Democrats, during an interview with Fox Business on Monday morning.

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Dean is due to testify later Monday as part of a series of hearings on special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE's Russia investigation, which are intended to further examine President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE's conduct as well as election interference by Moscow.

“To me, it’s indefensible,” Napolitano told the Fox Business hosts.

"I think it’s going to be a negative for the Democrats at the end of the day by the time the Republicans finish interrogating him. And of course, they can interrogate him about anything they want, they can interrogate him about the Nixon years,” he said.

Dean testified for the prosecution during the Watergate scandal, which helped contribute to the factors that led to Nixon's resignation from office. Dean later served jail time for his part in the cover-up.

Napolitano added that Dean's testimony would not be relevant as part of the look into Mueller's report.

“What he’ll say about Mueller and President Trump is nothing but his opinion,” Napolitano said. “I don’t know how relevant that is to a fact finder.”

Dean appeared earlier on CNN, where he is a contributor. He said he will testify that Trump's alleged obstruction of justice is "strikingly like Watergate."

"I'm clearly not a fact witness, but hope I can give them some context and show them how strikingly like Watergate what we're seeing now and as reported in the Mueller report is," Dean said.