President Donald Trump has claimed that pardons signed by his predecessor Joe Biden are invalid. His reasoning: They were allegedly signed with an autopen, a signing machine used by the U.S government for decades.

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.

Donald Trump says Joe Biden's last-minutes pardons via autopen are null and void. But what is an autopen? And what does it mean for pardons?