In the 32 previous instances when voters have been asked to decide a ballot initiative on same-sex marriage, we have lost every single time – even, notoriously, in California, where polling before the vote on Proposition 8 suggested otherwise. But things are changing fast. The president, hurriedly, got on board in May. At the Democratic convention next month, the party will adopt a platform calling for marriage equality. And in three states, it's looking as if 2012 will be the year gay marriage breaks its electoral losing streak.

This year, both Washington and Maryland adopted laws legalizing same-sex marriage, but homophobes have succeeded in postponing their enactment and getting a repeal on the November ballot. Surveys in both states have marriage equality winning by comfortable margins – and in Maryland, notably, African-American voters' preferences are statistically even.

Up in Maine, which rejected gay marriage at the ballot box in 2009, the same voters are now being asked to plump for equality, after all. It looks set to pass by a margin of 20 points. Better late than never.

There's a fourth marriage referendum in Minnesota, though this one is just the usual case of writing discrimination into the state constitution. Same-sex marriage is already illegal there, but legislators want to amend the charter to defend against "activist judges". As is now traditional, a smiling, Botoxed-to-death local news anchor, one Kalley Yanta, has become the voice of the discrimination movement, warning that schoolchildren may face a "homosexualist" indoctrination campaign. (In case you were wondering, this Yanta character also opposes birth control; she was on the pill once, and "God willing, if and when I make it to heaven when I die, I'm gonna meet those children that I killed due to my selfishness. And I'm gonna have some serious apologizing to do!")

Polling in Minnesota has been mixed, and the wording of the question is still unclear. But the fact that it's even close suggests that the homosexualist indoctrination campaign appears to be underway already.

So hooray, hooray: the tide is turning. But while I'm glad that more Americans are recognizing the need for equality, I wish it weren't being expressed through the toxic medium of the ballot initiative. Marriage is not a privilege conferred by voters or legislatures. It is "one of the basic civil rights of man", as the US supreme court wrote in Loving v Virginia, the 1967 case that struck down miscegenation laws, and civil rights are not at the disposal of voters.

We don't get to say who has them and who doesn't; we all have them. We call this equal protection – never a favorite constitutional clause among today's tricorn-wearing brigade – and the approval of a majority of voters on a given November day is not required.

I'd hate to think, the day after a few blue states legalize gay marriage via referendum, that we then have to respect the decisions of the 30 states who've done the opposite. Yet that's the argument many gay supporters are making – even at the top.

In his hasty interview with Robin Roberts, the president went out of his way, several times, to insist:

"I think it is a mistake to try to make what has traditionally been a state issue into a national issue."

He expressed no desire to overturn the recently adopted gay marriage prohibition in North Carolina. Rather creepily, Obama also said that he instructed the justice department to abandon the Defense of Marriage Act not because it discriminates against gays, but because it "tried to federalize what has historically been state law". We must hope that this was just political positioning, because as our law professor president surely knows, while marriage is a state affair, equality is a federal one. A class that faces discrimination enjoys constitutional protections that no state, and no state voters, can override.

Gays, incontestably, are one of these classes. But it has been fashionable, these past few years, to say that marriage is some inviolable quantity that courts cannot touch, that "unelected" judges have no right to abrogate "the will of the people". I suppose if you've never heard of constitutional democracy, you might find such an argument persuasive, but this is not how the United States deals with any other kind of discrimination. Democracy is a lot more complicated than voting – in this post-Citizens United mire, only more so.

"Let the people decide" is a favorite red-meat tactic of reactionary politicians who know that they have no legal authority to adopt the policy they'd like. But when it comes to marriage equality, the people have already decided. They did so back in 1868, when their state legislatures ratified the 14th amendment.

So, while it'll be nice for a few states to give the answer we'd like to hear come November, we have to start insisting that the right to marry isn't properly conferred by simple majorities in one state after the next. It has to come from Washington. And as the president himself has calculated, the country is ready for it.