In the first of these columns, in September 2010, I discussed one important reason our Constitution has endured: its capacity to respond to the profound changes the country has experienced over the past 225 years. These last three-plus years have been no exception.

Some of the changes involve technological innovation. For example, nearly every term, the Supreme Court confronts the question of how to interpret Fourth Amendment protections—which prohibit “unreasonable” searches or seizures—in an era that features powerful new tools for acquiring and using information. Two terms ago, in United States v. Jones, the Court held unanimously that police cannot attach a GPS device to a person’s car without a warrant. Last term, in Maryland v. King, the Court held that state officials can collect DNA samples from arrestees and compare that DNA to evidence in unsolved case files.

And this term, the Court is considering petitions on whether police can search an arrested individual’s smart phone without a warrant. (Disclosure: I help to represent the petitioner in one of the cases raising this question.) Police have long been entitled to examine items found within reach of the person they have arrested, both to protect officers’ safety and to prevent destruction of evidence. But the kind of evidence an 18th century suspect, or even a 20th century one, carried in his pockets was relatively limited. Today many smart-phone owners carry their most intimate information with them all the time—from family photographs to bank records to communications from doctors. If the Court takes on a smart-phone search case, it will again have to decide whether existing doctrine sufficiently protects constitutional values or whether new approaches are in order.

What has been striking about the Court’s recent Fourth Amendment decisions is not only that the level of constitutional protection varies dramatically among cases—the information acquired in a DNA sample is surely as personal as the information acquired by tracking where a suspect drives his car—but also that, in this area, conventional left-right distinctions among the justices often break down. In the DNA case, for example, Justice Breyer joined Justice Kennedy’s opinion for the Court, which treated DNA samples as materially similar to fingerprints, which are routinely collected upon arrest. Meanwhile Justice Scalia, aligned with Justices Ginsburg, Sotomayor, and Kagan, wrote a scathing dissent.

Strange bedfellows on the bench are a source and a sign of the Constitution’s flexibility. 

Another recent case that saw new coalitions on the bench was Hollingsworth v. Perry, one of the two same-sex marriage cases the Court ruled on last term. At issue was a California constitutional amendment, adopted by popular initiative, that restricted marriage to opposite-sex couples. After a federal district court held that the amendment was unconstitutional, state officials declined to appeal, leading some of the official ballot proponents—the handful of citizens who had gotten the initiative on the ballot—to appeal the ruling themselves. In Perry a 5-4 Court found they lacked the standing to do so.

The outcome raises profound issues of constitutional design at the state level. On the one hand, the majority in Perry pointed out that allowing the proponents to pursue the case on behalf of the state raised troubling possibilities. In his opinion for the Court, Chief Justice Roberts warned that, if the proponents’ standing were recognized, citizens would be free “to pursue a purely ideological commitment to the law’s constitutionality without the need to take cognizance of resource constraints, changes in public opinion, or potential ramifications for other state priorities.” These private citizens could scarcely be treated as representatives of the people of California. On the other hand, the purpose of the initiative process—a device the framers surely did not foresee and almost certainly would not have embraced—is to allow the people to circumvent the preferences of elected officials. The lineup in Perry defied stereotypes: the chief justice was joined in the majority by Justices Scalia, Ginsburg, Breyer, and Kagan; Justice Kennedy authored the dissenting opinion, joined by Justices Thomas, Alito, and Sotomayor.

Cases that produce seemingly strange bedfellows are both a source of the Constitution’s responsiveness to change and a signal of that change. When novel questions arise, judges may find that their preferred modes of interpretation provide surprising answers. Or they may reconsider whether existing doctrine remains faithful to basic constitutional principles. 

That was the case with respect to same-sex marriage. For many years, gay people were excluded from some of the most central institutions “We the people” have—from public service, from the armed forces, and from marriage. They were even excluded from the United States itself. In Boutilier v. Immigration & Naturalization Service (1967), the Supreme Court upheld a gay man’s deportation on the grounds that Congress could determine that gay people invariably suffered from a “psychopathic personality or a mental defect” that justified denying their naturalization petitions. 

Edith Windsor, the plaintiff in last term’s successful challenge to the federal Defense of Marriage Act, whom I helped to represent before the Court, faced these exclusions. As a pioneering woman in computer science during the 1960s, she would have been denied the job she sought to support herself during graduate school if an FBI background check had turned up the fact that she was a lesbian. So, too, Windsor was denied for decades the right to marry her life partner, Thea Spyer. And although Windsor and Spyer married in 2007, when Spyer died in 2009, the Defense of Marriage Act stripped Windsor of the tax deduction surviving spouses normally enjoy, forcing her to pay hundreds of thousands of dollars in estate taxes.

Justice Brandeis was fond of saying of the Court that “the most important thing we do is not doing.” By not deciding the merits of Perry while reaching the merits in Windsor, the Court did something important: it left space for further discussion of marriage equality, both in the courts and the country. One particularly telling example comes from New Jersey. Before Windsor, the state courts had held that New Jersey satisfied the demands of equality by providing same-sex couples with civil unions rather than the right to marry. After Windsor, they changed course, concluding that civil unions were inadequate, since they left couples without federal rights, benefits, and obligations.

As for not doing, another justice, Oliver Wendell Holmes, warned, “It is required of a man that he should share the passion and action of his time at peril of being judged not to have lived.” The same is true for women. And so I plan to take a leave of absence from my position as a professor and as a columnist for this magazine in order to work at the Civil Rights Division of the Department of Justice. I was inspired to go to law school by Simple Justice—Richard Kluger’s magisterial 1976 study of the litigation that led up to Brown v. Board of Education (1954). With so many civil rights issues to be addressed, the opportunity to participate more fully in the effort to realize the Constitution’s promise to “establish justice” for all is irresistible.