A lawsuit being heard this week in Pennsylvania could rewrite how the Defense of Marriage Act (DOMA) is applied across civil society, and potentially spark a dramatic expansion of the law's terms that would force private companies to not recognize same sex spouses.

The lawsuit boils down to benefits due to the spouse of Sarah Ellyn Farley, who died shortly after a legal same sex marriage to her wife, Jennifer Tobits, in Canada. Because the woman's parents refused to acknowledge their daughter's relationship with her wife, they claimed that DOMA requires death benefits accrued by their daughter at the Cozen O'Connor law firm be paid to them, instead of her spouse.

Responding to the suit, Cozen claimed something unique: that DOMA actually applies to private companies along with the federal government. In a counterclaim, Cozen asked the court to determine who should receive the payouts.

The case, Cozen O'Connor, P.C. v. Tobits et al (PDF), goes before a judge in Philadelphia on Monday.

"By making this novel argument, Cozen has pitted itself against countless employers across the nation, including many Fortune 500 companies that have provided equal benefits to their employees’ same-sex spouses for years," the National Center for Lesbian Rights explained in an advisory. "Those companies have never interpreted DOMA as applying to their private benefit plans."

If the court finds for Farley's parents, it will face a secondary consideration that weighs DOMA's redefinition against the U.S. Constitution -- a fight that LGBT activists all over the country have been gearing up for.

The Obama administration has said it does not agree with DOMA, and that it would not enforce the law or defend it in court. The Administration has also taken steps to introduce non-discrimination policies across all federal agencies, including the military, and to extend federal benefits to same sex spouses.