President Donald Trump on Monday said pardons issued by his predecessor Joe Biden were null and void because they had been signed by an autopen.
In a post on his Truth Social platform, Mr Trump said the pardons, particularly those issued for critics who had investigated him over alleged attempts to overturn his 2020 electoral defeat, were "void, vacant and of no further force of effect".
"Joe Biden did not sign them but, more importantly, he did not know anything about them!" he wrote. "The necessary Pardoning Documents were not explained to, or approved by, Biden. He knew nothing about them, and the people that did may have committed a crime."
An autopen is a mechanical device that replicates a handwritten signature. It is often used when a person needs to sign several documents in a row. In 2005, the Department of Justice issued an opinion stating "the President need not 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".
In the last days of his administration, Mr Biden issued pre-emptive pardons for former senior Republican legislator Liz Cheney, as well as other members of the congressional committee who had investigated Mr Trump's role in the January 6, 2021, attack on the US Capitol, as well as his alleged election interference.
The pardons were meant to provide blanket immunity to the legislators after Mr Trump, during his campaign, repeatedly threatened to seek "retribution" against his political opponents.
"A lot of journalists should be asking about whether or not the former president of the United States ... was cognitively impaired," White House press secretary Karoline Leavitt said. "The President was raising the point that, did the president [Mr Biden] even know about these pardons? Was his legal signature used without his consent or knowledge?"
Last week, Mr Trump said it would be "up to a court" to ultimately decide the validity of pardons signed via autopen.
The US President has heavily relied on executive orders to advance his agenda and has famously been using Sharpie pens when signing orders in the Oval Office in front of the media.