The biggest case the Supreme Court will decide this year went exactly as predicted: A packed house, colorful demonstrations outside the court, and virtually no access for anyone else. There was one unexpected glitch: At the end of the arguments by lawyer Mary Bonauto, who represented same-sex couples seeking a nationwide ruling on same-sex marriage, a protester interrupted the proceedings with a dire warning for the justices: “If you support gay marriage, you will all burn in hell.”

The demonstrator was quickly escorted out, but the moment illuminated the dynamics of Obergefell v. Hodges, a landmark case that should settle once and for all the legality of gay marriage—perhaps the biggest constitutional battle pitting civil and states’ rights since the Supreme Court decided Brown v. Board of Education more than 60 years ago. The court first took up the issue in 2013, when it voided the part of the federal Defense of Marriage Act defining marriage as between a man and a woman. But the arc toward equality for gays and lesbians began bending nearly 20 years ago, in Romer v. Evans, when a majority of the court ruled that the Constitution stood as a guard against the good intentions of a democratic majority willing to strip gays and lesbians of legal protections.

Against that backdrop, it was curious to hear the justices, including those on the court’s liberal wing, ask circumspect questions of Bonauto, a longtime advocate but a first-timer at the Supreme Court lectern. “What do you do with the Windsorcase, where the court stressed the federal government’s historic deference to states when it comes to matters of domestic relations?” fired Justice Ruth Bader Ginsburg, a staunch backer of gay rights and the first to raise tradition’s role in the proscription of marital relations. In that vein, other justices alluded to everything from same-sex relations in ancient Greece and Plato’s views to states’ prerogatives and the “millennia” of precedent where only opposite-sex marriage was enshrined at law.

Aside from a few moments where it seemed she was not addressing concerns by conservative justices, Bonauto held her poise—her argument was anchored on “the basic constitutional commitment to equal dignity” for gays and lesbians, the denial of which paints them with the “stain of unworthiness.” This tension between personal dignity and state autonomy to pass their own laws in family matters is the heart of what the justices will be deciding; it’s a conflict as old as the Constitution itself. Is it possible to grant a right to marriage to persons of the same sex, while not impinging on states’ prerogatives in the family sphere?

As if cognizant that court observers would be reading the tea leaves, it appeared the justices were unwilling to tip their hand in either direction. This explains why Justice Anthony Kennedy—author of every prior gay-rights victory and the expected swing vote in the case—made numerous appeals to the classic contours of marriage. “This definition has been with us for millennia,” Kennedy said. “It is very difficult for the court to say, ‘Oh well, we know better.’” Though one may interpret that as bad news for same-sex marriage, remember that Kennedy has had similar reservations in the past, and he’s come out on the side of equality every time.