The US supreme court did not issue any rulings on Monday. But that doesn’t mean that the justices – four calculating conservatives, four curious liberals and one very intriguing chief – didn’t make history. If you visit the court’s “fancy” new website, you will be able to read an eye-glazing list of cases it declined to hear on the first day of its new term. Hidden in this list is a major, major news story: same-sex marriage will soon be legal in a majority of American states.

Federal district and appeals courts have spent the last two years aggressively striking down bans on same-sex marriage. The supreme court was considering seven separate appeals to these rulings. Legal observers had been assuming that the court would use some or all of these appeals to hear an argument that would determine whether or not there is a federally guaranteed right to same-sex marriage. (The court ducked this question when it let stand a ruling that had held California’s infamous Proposition 8 initiative as unconstitutional.) Instead, the court threw a curveball, rejecting every single one of the appeals. And probably with good reason.

Progressives might prefer the supreme court to explicitly settle the question of same-sex marriage. The rest of the world might be wondering why the American legal system insists on such confounding workarounds. And same-sex marriage might not yet be a federal right, but Monday’s moves by the Roberts court represent the next best thing – and it is still an important victory for human rights.

The direct impact of this (in)decision is considerable. In several states, lower court rulings had been prevented from going into effect, but the supreme court’s rejection of these appeals makes the opinions final. As a result, gay and lesbian couples will have almost immediate access to the fundamental right to marriage in five states –Indiana, Oklahoma, Utah, Virginia and Wisconsin. This is particularly significant since all of those five states have Republicans in control of one or all of the executive and legislative branches – without judicial intervention, same-sex marriage wasn’t going to arrive any time soon. Hell, in Utah, making gay marriage legal through the political process is slightly less likely than Kayne West getting the Republican presidential nomination in 2016.

But the effects of the supreme court decision not to decide will be even more far-reaching than that, and marriage discrimination will soon be unconstitutional in 30 states. Those circuit court opinions holding same-sex marriage unconstitutional will also apply in “short order” to six additional states, including deep-red South Carolina, suddenly purple Kansas and redder-than-red Wyoming.

The supreme court, following its typical practice, did not offer any explanation for why it denied all the cases before it. Some day, from court documents or maybe even leaks by a former clerk, we might find out which of the justices wanted to hear the same-sex marriage cases and which didn’t. For now, it’s not unreasonable to speculate why the necessary four justices didn’t vote to hear at least one of the seven appeals.

For the court’s four most conservative members, the strategic calculation seems obvious. Justice Kennedy, the swing vote, has written several major rulings backing gay and lesbian rights, including last year’s historic ruling that the Defense of Marriage Act is unconstitutional. At times, he has seemed almost gleeful at sticking his figurative thumb in the eye of his more reactionary Republican colleagues – for example, in his landmark Lawrence v Texas opinion, he argued that a previous opinion upholding bans on “sodomy” was not only “not correct today” but was “was not correct when it was decided”, even though two justices who joined that opinion were still on the bench next to him. The Republican-appointed justices who remain hostile to LBGT rights – Justices Thomas, Scalia and Alito – presumably think that Kennedy, if he has to decide outright, will find that all state same-sex marriage bans violate the 14th Amendment Amendment. And they do not want to give him the chance to do that.

The more interesting question after Monday’s surprise: why did the supreme court’s four-member liberal block decide not to force the issue of same-sex marriage outright?

Well, the liberals may not be 100% sure about Kennedy’s vote. There is, after all, a difference between striking down rarely-enforced sodomy laws in a handful of states and requiring all 50 states to acknowledge same-sex marriage, leaving at least a hint of uncertainty about whether Kennedy is ready for the big next step.

But Ruth Bader Ginsburg, the leader of the court’s liberal wing, has repeatedly argued (erroneously in my view) that the court went too far, too fast on abortion rights – and that it’s better to proceed incrementally. Ginsburg and her colleagues – Justices Breyer, Kagan and Sotomayor – may well be happy to let lower federal courts decide same-sex marriage rights, reaching the same result in slightly slower motion. As long as federal circuit courts remain unanimous in finding bans on same-sex marriage unconstitutional, the supreme court’s liberals may see no reason to step in.

As for Chief Justice John Roberts, who knows how calculating he’ll be in defining a legacy, but this is one hell of an end-around.

Here’s the simple reality: States with millions of residents will now be required to legally uphold the basic rights of their gay and lesbian citizens. And the more same-sex marriage rights become entrenched, the less likely the supreme court is to retroactively take away these rights. Monday’s bizarre legal proceedings may not be the best-case scenario, but they are certainly the second best. And given that there’s even a small risk of catastrophe of an Anthony Kennedy-authored opinion that denies a constitutional right to same-sex marriage, inaction on Monday was arguably the most prudent step to a more equal tomorrow.