Adam Schiff says calling Hunter Biden would be 'an illegitimate abuse' of the Senate's impeachment trial

The House's top impeachment prosecutor said this week that calling in Hunter Biden to testify as a witness during the Senate's impeachment trial would constitute "an illegitimate abuse" of the process.

In an interview with "CBS Evening News" that was posted Tuesday morning, House Intelligence Committee Chairman and lead impeachment manager Adam Schiff (D-Calif.) said that, while it would only be fair for the president to be able to call witnesses, calling Biden would be a political effort immaterial to the case.

"It would certainly be fair for the president and his team to be able to call witnesses that can provide material information on the charges," Schiff told the network. "It would not be appropriate for the president to seek to call witnesses merely to try to perpetuate the same smear campaign that was foiled when his plot was discovered."

The scandal that precipitated the impeachment process, however, initially began with questions of Hunter Biden's employment as a board member at the Ukrainian energy company, Burisma Holdings, while his father, Joe Biden, was vice president and handling Ukraine policy for the Obama administration.

In case anyone forgot, Joe Biden once admitted to pressuring Ukraine's former president to fire the country's Prosecutor General Viktor Shokin, while Shokin was leading an investigation into Burisma Holdings. That vignette came up during the now-infamous July 25 phone call between President Donald Trump and Ukrainian President Volodymyr Zelensky, which was the subject of the whistleblower's complaint that triggered the House's impeachment probe.

But despite the role of his business dealings in the origins of the trial, Schiff told CBS that Hunter Biden "can't tell us anything about whether the president withheld military aid, whether he withheld that aid to coerce Ukraine to conduct political investigations. Or why he wouldn't meet with the president of Ukraine."

He added that the "only purpose in putting him on their list is they wish to trade material witnesses ... for immaterial ones that will allow them to continue to attack a political opponent."

As to which witnesses are actually relevant to the impeachment case, Schiff said, may end up falling to Supreme Court Chief Justice John Roberts, who is presiding over the trial.

"That's an illegitimate abuse of the trial," Schiff said. "And the chief justice, who may have an opportunity to rule on materiality of witnesses, as well as the senators, should not permit that kind of abuse."