A disciplinary rule aimed at curbing bias and discriminatory behavior by Pennsylvania attorneys had stirred up controversy before it was adopted earlier this year, and now it is drawing legal fire.

On Thursday, a Pennsylvania lawyer at a nonprofit focusing on Title IX due process issues sued members of the Pennsylvania Disciplinary Board, alleging that Rule 8.4, which the state Supreme Court adopted earlier this summer, will “chill his speech.” The lawsuit, filed in the U.S. District Court for the Eastern District of Pennsylvania by a lawyer from a Washington, D.C.-based legal nonprofit, alleges the rule violates the First Amendment and is unconstitutionally vague.