Former President Donald Trump’s claims of criminal immunity over his conduct in office are “novel,” “radical” and should be rejected, Special Counsel Jack Smith told the U.S. Supreme Court on Monday ahead of an historic hearing this month on whether his criminal case against Trump can proceed to trial.

Smith, who was appointed by U.S. Attorney General Merrick Garland, is seeking to prosecute Trump on four federal charges related to Trump’s efforts to overturn the results of the 2020 election. Trump has asked the Supreme Court to toss the case on the grounds that he enjoys presidential immunity over his official acts.