How a Mind-Blowing Number of Americans Came to Support Marriage Equality in a Short Time

When Ted Olson, the conservative super-lawyer who got George W Bush into the White House, went to federal court in 2009 to overturnCalifornia's gay marriage ban, the mood among gay rights groups was one of universal dread. The country was not ready, they wailed, and a negative ruling could set back the cause of equality for decades. What did this schmuck know about gay rights anyway?

But oh, how the mood has changed.

On Tuesday, Olson will walk up the steps of the US supreme court with the support not only of the entire gay establishment, but with a solid majority of the country behind him, too. Ten years ago, whenMassachusetts became the first state to legalize gay marriage (leading to death threats against the state's judges), 55% of Americans told pollsters that two men or two women had no right to marry, while only 37% favored equality. Today, the figures are almost exactly reversed. A full 58% of Americans now believe gays should be allowed to wed – and the trend goes in only one direction.

That figure rises to a breathtaking 81% among adults aged 18 to 29. And quite unlike the case of abortion, this progress cuts across party lines and political identification – even among Republicans and GOP-leaning independents, a majority of voters under 50 support marriage equality.

What's led nearly one in five Americans to come around from homophobia to tolerance?

Part of the victory is down to us – to gay men and lesbians who have come out, lived openly, agitated for change, and shown our families and colleagues every day that we deserve the full respect of the law. Asanother recent poll shows, people are substantially more likely to support marriage equality if they personally know someone who's gay or lesbian. Respondents cited other factors, from moral convictions to media representations, but the No 1 cause for rethinking opposition was a personal relationship with a gay person. Coming out works.

Another part of the massive shift in favor of gay equality derives from the piecemeal, state-by-state character of the marriage movement. It has been exhausting, at times farcical, to have to fight for a basic civil right in 50 different jurisdictions, with every brain-dead state legislator or local newscaster afforded his 15 digital minutes of bigotry. But the state-by-state legalization movement has had one major plus: it's removed the fear of the unknown from gay marriage, and allowed Americans to see – for a decade now! – that affording gays civil equality has no deleterious effect on private or religious life. Quite the opposite.

With public opinion shifting so decisively, and with progress continuing steadily at the state level, it may be tempting to say that a supreme court decision risks short-circuiting this advancement – even though gay marriage turns out to be wholly unlike abortion rights in its support across demographic lines. So said Rob Portman, the Republican senator from Ohio, when he announced his somewhat soft support for gay equality this month. But as his much braver son, Will Portman, argued this week in the Yale Daily News, marriage is not a private privilege, to be extended or denied at will.

It's much more than that: it's one of the "full rights of citizenship", and the right to wed "fits into a larger historical narrative" of public equality that stretches back to the 18th century. As Will Portman understands but his father does not, the fight for same-sex marriage is a fight for equality under the law – and that's what we all have to listen for at oral arguments this week and keep fighting for in the months ahead.

A reminder: there are two gay marriage cases at the high court, each contesting a different law. Tuesday is the hearing for Hollingsworth v Perry, which concerns Proposition 8 – the discriminatory California ballot measure that took away gay couples' right to wed in 2008. On Wednesday, in US v Windsor, the justices will consider the Defense of Marriage Act (Doma), the national law denying married gay couples the federal benefits of marriage, such as tax advantages or immigration rights.

Windsor is the easy one. Doma is so indefensible that the justice department doesn't even try anymore. The tougher case is Perry, and the outcome is probably down to one man: four justices are sure to support gay equality, while three are dead-set against.

John Roberts, the smiling firebrand, is a slightly hazier case. He has never ruled in a gay rights case before. His defense of Obamacare last year and his obvious concern for the long-term reputation of the courtlead some court observers wonder if he'd be reluctant to cast a vote that will surely seem bigoted in a few years' time.

Then, there's the juicy fact that his gay cousin will be in the chief justice's private seats during this week's hearings. But Roberts' solid conservative record – notably when it comes to matters of personal liberty – does not inspire confidence; he surely belongs in the no camp.

So, that's four and four. Which leaves Anthony Kennedy – the Reagan-appointed swing justice who wrote the two landmark gay rights decisions of the last 20 years. In Romer v Evans (1996), Kennedy ruled that a discriminatory measure in Colorado had no rational basis; in Lawrence vTexas (2003), he decided that sodomy laws were unconstitutional. In addition, he's a passionate defender of states' rights – meaning that Doma, all but dead already, is certainly headed for the scrap heap.

Despite his track record, though, it's too soon to say whether Kennedy has the stomach for a sweeping decision. Federalist that he is, he'll certainly bridle at a ruling that would legalize marriage nationwide. (Mindful of this, the Obama administration argued in its amicus brief for a more modest decision – legalizing gay marriage only in the eight states that already have civil unions.) And publicly at least, Kennedy remains a minimalist. During a visit to his hometown of Sacramento last month, Kennedy was asked about the court's frequent role in providing the final word on major political questions. He responded:

"I think it's a serious problem. A democracy should not be dependent for its major decisions on what nine unelected people from a narrow legal background have to say. And I think it's of tremendous importance for our political system to show the rest of the world – and we have to show ourselves first – that democracy works because we can reach agreement on a principle basis."

Rather an ironic statement, you might think, from a man who last year voted to overturn the entirety of Obama's healthcare reform law, the most important domestic legislation in 40 years, on the most pathetic of pseudo-constitutional grounds. But Kennedy was signaling something: that if he voids Proposition 8, he'll want to do it narrowly.

Perry offers two ways to do that. He could rule either, by following the ninth circuit's tightrope logic, that California is a special case, since gays could marry in that state before Prop 8 took that right away. Or he could say that the homophobes appealing that ruling simply lack standing in court.

Dismissing the Prop 8 case via a cop-out on standing is, alas, the most likely outcome. That would legalize marriage in California but say nothing about a broader right to marry.

But there is one good reason for cautious optimism. The court, and Kennedy in particular, have always been mindful of public opinion when it comes to questions of civil rights and social mores. As Michael Klarman, a Harvard law professor and former Ginsburg clerk, has shown at length, gay rights decisions have usually followed public opinion, not the other way around. And we know where public opinion is headed: swiftly, and inexorably, towards equality.

Olson goes to court Tuesday with the wind at his back, knowing that whatever happens this week, gay marriage will be legal nationwide soon. The question is when, and how. At age 76, Kennedy has one clear shot to write a decision that will go down in history as the most significant civil rights decision of our time – one that not only affords us the right to marry, but states once and for all that we are equal under the constitution.

I wouldn't plan a wedding in Mississippi yet – but we must hope Kennedy is tempted by the thought of that legacy.