Mark Osler, a law professor at the University of St. Thomas, spoke to the Washington Times and the New York Post about President Trump's claims against the validity of former President Biden's signatures on pardons due to the use of a machine-operated autopen rather than a signature by hand. Autopen signature have been used in the Oval Office for about half a century at this point.
From the stories:
"It would very hard to prove that Biden didn't know about these or it was done behind his back," Osler said.
Osler said that if Biden pardon recipients were to receive a subpoena as part of an investigation, they could challenge it in court by citing the sweeping comprehensive immunity conveyed by the ex-president.
