A Supreme Court decision not to take an appeal of a lower court ruling is generally (and correctly) recognized as not being a ruling on the merits by the nation's highest court. But yesterday's determination not to hear several lower court decisions on marriage is arguably an exception. It can be seen as significantly weakening the argument made by anti-equality advocates that a decades-old Supreme Court one-sentence ruling in a case called Baker v. Nelson prevents lower courts from addressing the constitutionality of marriage bans.

Baker was a one-sentence Supreme Court ruling from 1972. A gay couple had challenged Minnesota's ban on same-sex couples getting married, and they had lost in the state supreme court. They appealed, and the Supreme Court responded with a one-sentence order, dismissing the case "for want of a substantial federal question." Although it was just one sentence and done without oral arguments or a written opinion, the summary dismissal was nonetheless a decision on the merits of the constitutional issue. As a result, most of the lower courts that have addressed the same issue four decades later have had to contend with this case.

Especially since the Windsor case striking down DOMA, most judges have agreed that while the Supreme Court itself has not overruled Baker, doctrinal developments since 1972 on Equal Protection generally – and on anti-gay discrimination in particular – have completely undermined it. Normally, the Justices tell lower courts that only the Supreme Court can overrule a Supreme Court precedent. Until that happens, lower courts should consider themselves bound by the precedent, even if the high court has undermined it over the years. But it has also made an exception if the precedent is, like Baker, a summary dismissal. In that case, courts do not have to follow it if subsequent doctrinal developments indicate it is no longer good law. That's what has allowed so many courts to get to the merits of the constitutional challenges to marriage bans.

Yesterday arguably represents another step in Baker's demise. Several landmark rulings over the past twenty years have recognized the fundamental equality, liberty, and dignity of lesbians and gays, making it hard to say that the Court still considers marriage equality lawsuits as not even presenting "a substantial federal question."

A more direct rebuke of Baker occurred when the Supreme Court issued an order accepting certiorari in the Proposition 8 case, which presented the exact same issue as the older case. Even though the Justices ultimately didn't address the merits, it is hard to claim with a straight face that the Supreme Court accepted cert and engaged in spirited oral arguments on an issue where there was no substantial federal question.

Yesterday's dismissal of the marriage cases represents another important stage in the long death of Baker. Three circuit courts concluded they could address the merits of the marriage equality arguments, Baker notwithstanding. Just by considering the issue, they rejected the holding of Baker. And certainly the conclusion they reached – that the United States Constitution prohibits states from banning same-sex couples from marrying – is a direct repudiation of the older case.

The Supreme Court takes it very seriously when a lower court simply disregards its precedents and says they are no longer good law. It's fine for a lower court to distinguish a case from an important previous precedent – that happens all the time. But to say the precedent can now be ignored would be a major challenge to the Supreme Court's authority … if the Justices thought for a minute that the old case was still good law.

But yesterday's decision sends a powerful message about Baker. A majority of Justices voted not to take the cases. If a majority considered Baker good law, we would not likely have seen an official Court action supported by a majority of the Justices choosing not to hear cases where lower courts declared themselves not bound by the precedent.

As additional circuit courts consider challenges to state marriage bans, they should not consider themselves bound by Baker v. Nelson.