A gay former vice principal at a Seattle Catholic school is suing his former employer, after they fired him for getting married.

Mark Zmuda was fired from his job at Eastside Catholic School in December after staff discovered he had married his same-sex partner, but he was told he could have his job back if he divorced.

After a petition to have him reinstated gathered over 50,000 signatures, the school’s president resigned “after much prayer and reflection”.

Zmuda is now suing both Eastside Catholic School and the Seattle Archdiocese for discriminating against him, and for wrongful termination.

He pointed out that the school’s employee handbook states: “Eastside Catholic school does not discriminate on the basis of an employee’s or applicant’s race, religion, creed, color, sex, age, national origin, disability, marital status, sexual orientation or any other status or condition protected by local, state or federal law”, though the clause has since been removed from the school website.

According to The Guardian, the school’s lawyers, Michael Patterson and Andrew Weinberg, told the court that a judgement from the court would violate the First Amendment, as “in order to make a discrimination determination, the court would be forced to delve into Catholic doctrine on the definition of marriage”.

They say this would violate the school’s “first amendment right to make its own decisions relating to matters of faith and doctrine.”

Zmuda’s attorney Richard Friedman said: “No one is saying they can’t discriminate against gay people. If they had said, ‘we are going to adhere to church doctrine, and not hire gay people, people on birth control, or people who get divorced’, they can do that.

“What they can’t do is tell people they don’t discriminate, and have people rely on that representation, and then change it on them. You have to treat employees fairly.”