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.

O n Monday, President Donald Trump signaled that he intends to nullify the presidential pardons—issued to those on the House Jan. 6 committee that investigated Trump—executed by President Joe Biden because, he said, they were signed via autopen.