In a letter earlier this month, a popular music teacher at St. Ann Catholic School in Missouri told students' parents of "my joyful news, and my sad news." The good news was that Al Fischer had plans to soon marry his partner of two decades in New York, one of six states in the union where same-sex marriage is legal. The bad news, reports the St. Louis Post-Dispatch, was that after four years, "I can't be your music teacher anymore."

When church officials learned of Fischer's plans to wed his male partner, they told him that he had to leave his post in three weeks -- on the day of the couple's planned wedding and 20th anniversary together. Fischer's partner, Charlie Robin, posted on Facebook that Fischer was being fired "for marrying a man, in another state, even though in the state of Missouri we will continue to be just good friends."

Fischer was then fired the next day.

According to Robin, executive director of Washington University's Edison Theatre, their relationship was well-known at the school, and he attended faculty parties and school concerts. Fischer was also the artistic director of the Gateway Men's Chorus, a 24-year-old singing group that "affirms and promotes gay culture and acceptance," and "proclaim[s] to the world that a voice like ours can never be silenced."

Fischer was only dismissed, claims Robin, because a representative of the St. Louis Archdiocese overheard him discussing his wedding plans with co-workers. All Catholic educators in the Archdiocese of St. Louis are required to sign the Christian Witness Statement, which states that they must "demonstrate a public life consistent with the teachings of the Catholic Church."

Robin is a practicing Catholic, but the church teaches that homosexual acts violate divine and natural law. Men and women with gay inclinations "must be accepted with respect, compassion, and sensitivity." But if those men and women act on those desires, it's another story. in his 2005 book, Pope John Paul II called gay marriage "a new ideology of evil."

"With full respect of this individual's basic human dignity, this same-sex union opposes Roman Catholic teaching as it cannot realize the full potential a marital relationship is meant to express," wrote Rev. Bill Kempf, St. Ann's pastor, in an emailed statement to the St. Louis Post-Dispatch. A spokeswoman said the archdiocese fully supported the decision.

In Missouri, as in 28 other states, it's legal to fire, demote or refuse to hire someone for being gay. Missouri was also the first state to enact a constitutional amendment banning gay marriage. The 2004 referendum picked up over 70 percent of the vote.

In July 2010, Missouri Gov. Jay Nixon passed an executive order that banned the discrimination of public employees on the basis of sexual orientation, but this wouldn't apply to a Catholic schoolteacher.

"Missouri isn't a very friendly place for a gay discrimination case," Russ Riggan, a St. Louis employment lawyer, told AOL Jobs. "It's very employer friendly -- not employee friendly."

The city of St. Louis, on the other hand, passed an ordinance 20 years ago that banned discrimination in employment, as well as housing, credit, education, and public access based on sexual orientation. The New York Times called it then "one of the strongest gay-rights laws in the nation."

Unfortunately for Fischer, St. Ann Catholic School is in north St. Louis County, a couple of miles from the city proper. "I don't see a legal claim that employee would have," says Riggan.

Even if St. Ann was covered by the ordinance, it's possible that Fischer wouldn't have a legal claim anyway, because employment discrimination laws do not apply to religious offices. In January, the Supreme Court unanimously ruled that a Lutheran school did not break any laws when it fired one of its teachers after she took disability leave, because she was a "minister" and therefore exempt from the Americans With Disabilities Act.

It was ambiguous in the ruling, however, how exactly a "minister" is defined. The woman in this case was deemed one by the courts because she was ordained, taught religious classes, conducted chapel services, and led students in daily prayer. It's unclear whether Fischer, a music teacher, would meet the court's criteria for "minister."

A parent told the St. Louis Post-Dispatch that Fischer's sexual orientation was well-known, and that many parents were upset over Fischer's firing. "A family conversation about whether or not justice was served here could be a great thing," Fischer said in his letter to parents. "I do not want the lesson from this for the kids to be, 'Keep your mouth shut, hide who you are or what you think if it will get you in trouble.' "