But according to the U.S. Constitution, the President has no such authority to overturn his predecessor’s pardons, especially not based on the type of signature, legal experts say. “The Constitution doesn't even require that the pardon be written, so the idea that the signature is by autopen rather than by handwritten signature seems not relevant to the constitutionality because Article II just says that the President has the power to pardon,” says Bernadette Meyler, a Stanford Law School professor and constitutional law expert.

Autopen is an electronic signature that allows individuals to sign a document without physically being there. The signature mimics a handwritten signature, but is done by a computer. A vast number of statutes and other documents have been signed by autopen, experts say. For instance, former President Barack Obama signed a national security measure via autopen while he was in France. Meyler says that if presidential pardons were to be invalidated because of an autopen signature, that could bring into question other policies that were signed by such measures. “When so much is being automated and put online, requiring some literalness in the signature really would be a step backwards," she says.

A 2005 guidance from the U.S. Department of Justice (DOJ) noted that a President does not need to “personally perform the physical act of affixing his signature to a bill he approves and decides to sign in order for the bill to become law. Rather, the President may sign a bill within the meaning of Article I, Section 7 by directing a subordinate to affix the President’s signature to such a bill, for example by autopen.”

Jeffrey Crouch, a professor at American University, told Axios that pardons are final so long as they are valid......

If Trump were to try to prosecute someone who received a presidential pardon, experts say the case would likely go to courts, where Trump’s actions are unlikely to stand. “I can't imagine the court saying that it wasn't a valid pardon because of the autopen issue,” says Meyler. “Biden made statements regarding these pardons, so it would be hard to show that they weren't a decision of the President.”