The Trump filing relies heavily on a 2012 Supreme Court ruling in United States v. Alvarez that says Xavier Alvarez, an elected official, could not be prosecuted for his false claims that he was awarded a congressional medal for bravery. The Supreme Court said that he had a right to lie, including claiming to be a U.S. Marine who had fought for his country.

Source: Donald Trump’s Lawyers Say That False Statements Are Free Speech