Updated at 10:05 a.m. Wednesday to correct Judge Teitelman's first name.

Updated with comments from the American Civil Liberties Union of Missouri.

The Missouri Supreme Court has ruled that a gay man whose longtime partner, a state trooper who was killed in the line of duty, is not eligible for the trooper's survivor benefits because the two were never married.

Trooper Dennis Englehard was assisting a stranded motorist on Christmas Day 2009 when he was struck and killed by a car that lost control on icy roads. His partner of 15 years, Kelly Glossip, sued after he was denied survivor benefits, which by law are limited to a surviving spouse. Glossip argued that was discriminatory because Missouri state law also forbids same-sex marriage.

"We're disappointed, but we do think it helps highlight the discrimination that's ongoing in Missouri against gays and lesbians," said Tony Rothert, the legal director for the American Civil Liberties Union of Missouri and one of Glossip's attorneys.

In a 5-2 opinion, the court ruled that the law Glossip was challenging discriminated on the basis of marriage, not sexual orientation. "Glossip was denied survivor benefits because he and the patrolman were not married," the court wrote. "If Glossip and the deceased patrolman had been married in another state (or country), Glossip could have challenged the statute that prohibits recognizing same-sex marriages for purposes of Missouri benefits. But they were not."

Rothert says he is aware of same-sex couples who were married in other states and cannot access state benefits, but did not say if the organization is planning another legal challenge.

In a scathing dissenting opinion joined by Judge George Draper, Judge Richard Teitelman argued that the majority ignored the fact that state law "employs a definition of spouse that operates to the unique disadvantage of gay men and lesbians, even when, like Corporal Engelhard, they devote their lives to the defense of the same rule of law that relegates them to the status of second class citizens."

Rothert says the impact of the ruling goes far beyond the denial of benefits, which would have helped Glossip financially.

"I just can’t imagine losing your partner, having the state say that you were strangers, and having the Missouri Supreme Court say that’s okay," Rothert said. I think that’s the most painful part of the decision for him."

Background on the Glossip case can be found here.

Read the Court's opinion here.

Follow Rachel Lippmann on Twitter: @rlippmann