On Tuesday morning at the U.S. Supreme Court, Charles Cooper of Cooper and Kirk was no more than a sentence into his spiel on the sanctity of traditional marriage when Chief Justice John Roberts interrupted with the request that he first address a more prosaic issue: Do Cooper’s clients, as leading proponents of the 2008 California ballot initiative that banned same-sex marriage, even have standing to defend the initiative, known as Proposition 8, in federal court? By the time oral arguments concluded more than an hour later, it seemedlikelier than not that the court would avoid a sweeping ruling on equal protection under federal law for gays and lesbians – and that they’d do it via a finding that Cooper’s clients did not have standing to bring an appeal.

That holding, which was advocated by lawyers for the same-sex couples who sued to invalidate Prop 8, would assure gays and lesbians the right to get married in California. But it would also implicate some difficult issues that the Supreme Court has not previously addressed. What qualifies someone to act as an agent of the state for the purposes of defending a ballot initiative? If state officials choose not to defend a law passed by the voters, may private citizens who backed the initiative act on the state’s behalf? And if the law’s private proponents don’t have federal standing, does that mean state officials have the de facto ability to undo voter-passed laws they don’t support? If the Supreme Court answers these questions in its Prop 8 decision, the ruling may end up being better remembered for setting precedent on standing, stage agency and ballot initiatives than for civil rights.

To understand why, you have to know a little about the procedural history of the case. In 2009, six months after California voters passed Prop 8 and amended the state constitution to ban same-sex marriage, two same-sex couples filed a suit in federal court in San Francisco against the state officials tasked with enforcing the ban. The complaint, filed with great fanfare by Theodore Olson of Gibson, Dunn & Crutcher and David Boies of Boies, Schiller & Flexner, asserted that Prop 8 violated the Equal Protection and Due Process clauses of the 14th Amendment. The state officials named in the suit chose not to defend the law’s constitutionality, but U.S. District Judge Vaughn Walker (now retired) permitted private citizens who had championed the law to intervene as defendants. After a 12-day bench trial in 2010, Walker found Prop 8 to be unconstitutional.

California’s governor and AG declined to appeal Walker’s ruling, but the law’s backers asked for review at the 9th Circuit Court of Appeals. The appeals court, in turn, asked the California Supreme Court for an opinion on whether private proponents of a ballot initiative have authority to defend the law’s validity when the state refuses to. In November 2011, the state Supreme Court held that they do. Allowing ballot initiative proponents to stand up for their law, the court said, assures that judges will hear the full range of arguments for and against the law and that voters who enacted the measure won’t be subject to “any residual hostility or indifference of current public officials.” Citing the state Supreme Court’s holding, as well as the U.S. Supreme Court’s 1987 ruling in Karcher v. May that individual New Jersey legislators had authority to represent the state’s interests in litigation, the 9th Circuit concluded in February 2012 that Prop 8 proponents had standing to appeal, but that Judge Walker properly held the law to be unconstitutional.

Obviously, when backers of the ballot initiative asked the U.S. Supreme Court to take the case, they didn’t highlight the controversy over their standing to appeal in federal court. But when the court granted certiorari, the justices specifically directed both sides to brief and argue the question. That’s not a surprise, given the chief justice’s keen interest in constitutional standing. Justice Ruth Ginsburg, moreover, previously noted the court’s “grave doubts” about the standing of ballot initiative proponents to pursue federal-court appeals in the 1997 case Arizonans for Official English v. Arizona, though the case was decided on other grounds.