Lawyers for former President Donald Trump are arguing that attempts to kick him off the presidential ballot under a rarely used constitutional clause for engaging in “insurrection” are improper attempts to interfere with his freedom of speech.

DENVER (AP) — Attorneys for former President Donald Trump argue that an attempt to bar him from the 2024 ballot under a rarely used “insurrection” clause of the Constitution should be dismissed as a violation of his freedom of speech.

The lawyers made the argument in a filing posted Monday by a Colorado court in the most significant of a series of challenges to Trump’s candidacy under the Civil War-era clause in the 14th Amendment. The challenges rest on Trump’s attempts to overturn his 2020 loss to Democrat Joe Biden and his role leading up to the violent Jan. 6, 2021, attack on the U.S. Capitol.