Dear Justice Kennedy

Why the courts, not lawmakers, will deliver gay marriage.

Revelers display U.S. and gay pride flags as they celebrate early election returns favoring Washington state Referendum 74.

People celebrate early election returns favoring the Washington referendum that would legalize gay marriage at an impromptu gathering in Seattle on Nov. 7, 2012.

Photo by Ted S. Warren/AP

One of the few persuasive points that opponents of same-sex marriage made in last week’s Supreme Court arguments was that gay couples should rely on the political process—not the courts. In the argument over California’s same-sex marriage ban, passed by voters in 2008, Justice Samuel Alito asked, “Why should it not be left for the people, either acting through initiatives and referendums or through their elected public officials?” The next day, in the argument over the Defense of Marriage Act, enacted by Congress in 1996, Chief Justice John Roberts added a twist to the popular sovereignty point. “The lobby supporting the enactment of same-sex marriage laws in different states is politically powerful,” he said, adding that “as far as I can tell, political figures are falling over themselves to endorse your side of the cause.”

Although it’s superficially appealing, the argument for judicial deference is wrong. The ability of gay rights groups to win ordinary political battles is actually quite limited. Much more common than the imposition of pro-gay policies on a disapproving majority is the reverse scenario: the failure to enact such policies even when they’re supported by a popular majority. Judicial intervention may therefore be necessary because, regrettably, this is not an area in which the political process can be trusted.

In pioneering recent work, Columbia political scientists Jeffrey Lax and Justin Phillips have found that politicians exhibit a sharp conservative bias on gay rights issues. That is they do not become at least 50 percent likely to vote in a pro-gay direction until their constituents’ support for doing so is substantially higher than 50 percent. In the 2010 vote on repealing the military’s “don’t ask, don’t tell” policy, for example, House members became 50 percent likely to vote yes only when 60 percent of their constituents supported repeal. In the 2007 vote on the Employment Non-Discrimination Act, which would have banned anti-gay discrimination by employers, House members were more likely to vote yes only when 70 percent of their constituents favored the bill.

The story is similar at the state level. It takes close to 60 percent support among the public before a state becomes 50 percent likely to authorize civil unions for gay couples. It takes close to 70 percent support before a state becomes 50 percent likely to ban anti-gay hate crimes. And about 80 percent support is necessary for a state to become more likely than not to protect gays from housing discrimination.

For lawyers, these findings bring to mind the most famous theory of judicial review of the past half-century: law professor John Hart Ely’s view that courts should intervene in social or economic disputes only when incumbents are entrenching themselves in office or a minority group is unfairly disadvantaged in the political process. Gay rights issues do not raise entrenchment concerns, but they squarely present the problem of a minority group that is politically handicapped. In fact, it’s hard to think of better evidence of a handicap than the consistent failure to pass pro-gay policies even when a majority of the public supports them. Contrary to Alito and Roberts’s claims, then, ordinary politics is not working properly in this area. That’s why the courts may be needed to step in.

What about the 2012 victories for same-sex marriage in Maine, Maryland, and Washington State, or the polls showing that a majority of Americans now support it? These are very encouraging developments, but they are also very recent and incomplete. Same-sex marriage remains completely banned in 31 states, even though a majority is in favor of it in several of those places. If anything, the fact that most Americans support same-sex marriage but only nine states and the District of Columbia have enacted it further confirms that public opinion hasn’t translated into public policy. True, it’s possible that the rising popularity of same-sex marriage will prompt many more states to embrace it, thus erasing the conservative bias against its adoption. But this is all speculation about the future. For the moment, it’s clear that gay rights groups need much more than majority support to win their political fights.

Of course, there are other areas in which popular majorities often don’t get what they want. According to Lax and Phillips, mismatches between what the public supports and what laws pass are common in fields like education, health care, and law enforcement—sometimes with a bias toward the right and sometimes toward the left. But there’s no danger that if the courts intervene in gay rights disputes, they’ll also have to get involved in all those other issues. They don’t involve a disadvantaged minority group akin to gays. Ely would tell the courts: Keep out.

This is not to say that the Supreme Court should rule in favor of same-sex marriage simply because majority support is often insufficient to pass it. Under the court’s previous decisions, a group’s political power matters much less than more familiar concepts such as individual liberty and equal treatment under the law, as the Constitution guarantees it. These concepts should (and almost certainly will) be the focus of the court’s rulings in the gay marriage cases. The point, rather, is that as they weigh these cases, the justices should not be lulled into complacency by the recent successes that gay rights groups have achieved. However heartening, those wins do not change the reality of a broken political process that only the court can fix.

Read more from Slate’s coverage of gay marriage.