When Margery Brown was dying of ovarian cancer, she wasn’t concerned about herself.

She was worried about how her same-sex partner of 27 years, Helen Thornton, would make ends meet after she was gone. The year was 2006 and same-sex marriage was not yet legal in the state of Washington where the couple jointly resided, which meant that Thornton would be unable to collect survivor’s benefits from Social Security.

Brown, who worked at Evergreen State College, had been the breadwinner. She and Thornton had bought a home together and started paying off the mortgage. Thornton had given birth to their child in 1984, and Brown had legally adopted him—a boy named Asa who was entering his twenties when Brown received her diagnosis.

They were, simply put, a family. Thornton was even quoted in a newspaper article saying that she would marry Brown if only it were legal.

But even now that same-sex marriage is legal nationwide, Thornton—like many in the LGBT community who lost long-term partners before marriage equality came to their states—cannot receive the same survivor’s benefits that heterosexual widows and widowers can get after their spouses pass away.

That’s why LGBT advocacy group Lambda Legal filed a landmark lawsuit against the Social Security Administration last week on Thornton’s behalf, arguing that SSA’s denial of survivor’s benefits violates Thornton’s constitutional right to equal protection.

“ The money is certainly important. The bigger issue for me is that it’s an issue of fairness and equality. ” — Helen Thornton

For Thornton, who is living on a fixed income, an additional $700 a month would be life-altering. But she told The Daily Beast that the case is about much more than that.

“The money is certainly important,” she said. “The bigger issue for me is that it’s an issue of fairness and equality.”

The precedent the case might set is very much on Thornton’s mind: Although the Supreme Court legalized same-sex marriage through Obergefell v. Hodges in 2015, there has so far been no remedy for LGBT people in Thornton’s position, who had relationships with their now-deceased partners that were effectively marriages in everything but name only.

“We were spouses,” Thornton said. “We bought a house together. We had a child together. I was part of her family; she was part of my extended family. So in all senses of the word, we were a couple—we just weren’t allowed to have that legal document that really protected us.”

For Lambda Legal senior attorney Peter Renn, the lawsuit has been a long time coming.

“This issue is something that we’ve been monitoring at Lambda for a couple years now because this problem is definitely not new,” he told The Daily Beast. “The only reason why it’s being filed in 2018 as opposed to say, in 2015, is because the process of exhausting your administrative remedies in front of Social Security just takes quite a long period of time.”

Thornton told The Daily Beast that she first applied for survivor’s benefits in January 2015, when she was about to turn 60–and didn’t receive a final denial from the Social Security Administration until July of this year.

Only then could she proceed with the case, which could potentially impact a number of LGBT people who lost their partners prior to the legalization of same-sex marriage.

“We’ve gotten a number of calls to our help desk from people who are in a similar situation,” Renn told The Daily Beast. “So our hope is that the relief we obtain through this case will not just help Helen, but help other people who are in a similar boat.”

The case brings out particular passion in Renn, who sees the issue as one affecting “the most vulnerable people in our community,” namely LGBT elders, who are more likely to be facing social isolation.

What animates Renn the most is the fact that LGBT elders—like their non-LGBT counterparts—have been paying into Social Security for their entire working lives, only to be denied survivor’s benefits when their partners die.

“So, in essence, same-sex couples have for a very long time essentially been subsidizing survivor’s benefits for heterosexual surviving spouses,” Renn told The Daily Beast. “And the whole point of the system is that it’s supposed to benefit you in retirement—and at the very least you should get an equal shake to the benefits that you pay into with your own income.”

The Social Security Administration did not immediately respond to The Daily Beast’s request for comment on the lawsuit.

According to Lambda Legal’s complaint [PDF], SSA denied Thornton’s application “on the grounds that she was not married to Ms. Brown, even though that was a legal impossibility in Washington” during their relationship. Same-sex marriage wasn’t legalized in Washington State until December 2012, when a new state law superseded the state’s longstanding Defense of Marriage Act.

The Lambda Legal complaint essentially makes the argument that SSA can’t rely on state laws that have since been deemed unconstitutional by the United States Supreme Court in order to deny survivor’s benefits to people in Thornton’s position.

States cannot deny marriage-related benefits to same-sex couples, the logic goes, and “essentially, the federal government can’t do the same thing,” Renn told The Daily Beast, even if those couples could not legally be married in the past.

If Lambda Legal succeeds in establishing a broad precedent in this area, SSA could end up having to make determinations about whether any given same-sex relationship that predated marriage equality could be viewed in hindsight as a marriage.

“I think the legally relevant question should be: Would this particular same-sex couple have married if given the opportunity to do so?” Renn explained, noting that SSA could gather information from wills, from the testimony of the surviving same-sex partner, or from information about the couple’s living situation or public presence.

That may sound like a fair bit of fact-finding but Renn argues that it would be more or less routine for an SSA accustomed to performing investigations: “It definitely turns on facts—and the facts might vary from person to person—but at the end of the day, the Social Security Administration makes these factual determinations all the time.”

In Thornton’s case, gaining access to survivor’s benefits would allow her to live more comfortably. Since Brown’s death, as the complaint notes, Thornton has lived off of her personal benefits from Social Security—about $900 per month—and “a modest amount of income she earns from taking care of animals.”

“ When your partner’s dying, you’re focused on them and taking care of them. But once they’re gone, then the reality of all the other stuff hits you. ” — Helen Thornton

Thornton’s financial situation, as she told The Daily Beast, did not fully come into focus until Brown had passed away.

“When your partner’s dying, you’re focused on them and taking care of them,” she said. “But once they’re gone, then the reality of all the other stuff hits you. Once they’ve died and you’re not the caretaker, you do start thinking about the financial end of things.”

Thornton says that she feels “lucky” to still be living in the house she shared with Brown.

“I have been able to pay the mortgage but there’s been times since I lost Margie that it’s been a struggle to make mortgage payments,” she said.

Thornton hopes that more attention can be paid to issues like this one that affect LGBT elders. Hers, after all, is the generation that fought for marriage equality, but in a post-Obergefell world, plights like Thornton’s have barely entered public consciousness.

“In our society, we’re pretty obsessed with youth,” she said. “We’re kind of a youth culture—and so I don’t think, in general, we’ve spent enough time thinking of what happens to all of us when we’re elderly, when we’re seniors.”

For same-sex couples who loved each other in sickness and in health while subject to an unconstitutional ban on same-sex marriage, Renn says, granting survivor’s benefits is the least the federal government can do.

“Helen and Marge were denied the dignity of marriage for the 27 years that they were a committed couple,” he told The Daily Beast. “And now Helen is being denied the dignity of equal treatment as a widow by her own government. That is just a slap in the face.”