Presidents of both major parties have used the device and experts called into question legality of Trump’s move

Donald Trump said on Tuesday he is terminating all documents, including pardons, that he said his predecessor Joe Biden signed using an autopen – an unprecedented attempt to rollback a previous president’s actions using what legal thinkers view as a flimsy pretext.

The autopen is a device used to replicate a person’s signature with precision, typically for high-volume or ceremonial documents. It has been employed by presidents of both major parties to sign letters and proclamations.

Legal scholars broadly agree the constitution does not require a president to physically sign many documents, including pardons, with their bare hands to make them legally enforceable, according to PolitiFact. Federal law also lacks a mechanism for a president to overturn a previous president’s pardon.

Trump and his supporters have made a variety of unfounded claims that Biden’s use of the device while president invalidated his actions or suggested that he was not fully aware of these actions. It is not known whether Biden used an autopen on pardons.