There are good reasons for a lawyer to avoid insulting an opponent in court filings, Judge Amul Thapar of the U.S. Court of Appeals for the Sixth Circuit wrote in an opinion Thursday. But the most important reason, he declared, is that “colorful insults” did nothing to prove his clients had the right to bring their lawsuit in the first place.

Thapar, writing for a unanimous panel, leveled pointed criticism at a Tennessee lawyer who, in the court’s view, had gone too far in disparaging his opponents in an antitrust suit against Ballad Health, the Medical Education Assistance Corp. (MEAC) and various individuals.