President Donald Trump questioned former President Joe Biden’s autopen-signed pardons, calling them “void," as experts weigh whether courts could rule on the validity of presidential clemency.

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.

President Donald Trump claimed Monday that pardons recently issued by Joe Biden to lawmakers and staff on the congressional committee that investigated the Jan. 6, 2021, Capitol riot have no force because the-then president signed them with an autopen instead of by his own hand.