The use of the autopen, a device that reproduces signatures and is ubiquitous in government and business, is ordinarily uncontroversial. There is no power to undo a pardon in the Constitution or case law.

The flurry of pardons issued by President Joe Biden in his final days looks poised to face a legal challenge by the Trump administration because of the way he signed them.Legal experts say the law is clear on the use of autopen,

President Trump has said "many" pardons issued by Joe Biden are void because the former president signed them with "autopen" - a device which reproduces a person's signature - rather than by hand.Trump did not provide evidence for his claim - which was posted on Truth Social.