HARTFORD, Conn. – A federal judge has been asked to recuse himself from a lawsuit that seeks to block the participation of transgender athletes in girls' sports after he ordered the plaintiffs' lawyers not to refer to them as biological males.

The plaintiffs argue that U.S. District Court Judge Robert Chatigny showed bias during a conference call last month when he ordered them to use the term transgender female, which he said was "consistent with science, common practice and perhaps human decency."

The attorneys from the Christian nonprofit organization Alliance Defending Freedom represent four female runners who contend that transgender athletes have an unfair biological advantage that violates Title IX, the federal law that allows girls equal educational opportunities, including in athletics.

The lawyers for the female runners refer to the transgender athletes as males or biological males throughout the lawsuit, which seeks to block a state policy that allows students to compete as the gender with which they identify.

"In short, the court's order and comments during the hearing would leave an impartial observer gravely concerned that the court has prejudged the matter, rejected core aspects of plaintiffs' case before hearing the evidence and legal arguments, and assumed the role of advocate for the defendants," the plaintiffs' attorneys wrote in last week's filing.

Judge Chatigny has not indicated when he might rule on the motion to have him removed from the case.

The Connecticut Interscholastic Athletic Conference, which oversees high school sports in the state, has said its policy is designed to comply with the state's law barring schools from discriminating against transgender students.

The plaintiffs have asked for a hearing that would allow for a ruling on an injunction blocking the participation transgender girls before next winter's indoor track season.

They had been seeking to block two transgender runners from participating in the spring track season and to erase the records they hold from the state's record books.

The spring season has since been canceled because of the COVID-19 pandemic and the two transgender athletes are scheduled to graduate next month.

The two seniors have combined to win 15 girls state indoor or outdoor championship races since 2017, according to the lawsuit.

Both transgender athletes are receiving hormone therapy as treatment for gender dysphoria, and both have hormone levels that are typical for non-transgender girls, their lawyers have argued.