1.

The Roberts Court, which just concluded its ninth term, was officially launched on September 29, 2005, when Justice John Paul Stevens administered the oath to the newly confirmed chief justice, John Roberts. In a more significant sense, however, the Roberts Court’s birth—or at least conception—should be dated five years earlier, to December 12, 2000. That’s the day the Supreme Court decided Bush v. Gore, ending a recount of the too-close-to-call Florida presidential vote, and ensuring that George W. Bush would become president with half a million fewer popular votes than Al Gore. The Court’s five conservatives—William Rehnquist, Anthony Kennedy, Antonin Scalia, Sandra Day O’Connor, and Clarence Thomas—relied on a wholly unprecedented theory of the Constitution’s guarantee of “equal protection of the laws,” which they announced would apply this one time only, to block the Florida recount, and President Bush took office.

Bush was reelected in 2004, this time without needing the Supreme Court’s help, and that meant that when Justice O’Connor announced her retirement and Chief Justice Rehnquist died in office in 2005, President Bush, not Al Gore or a successor, had the privilege of appointing two new justices and shaping the Court for years to come. Had a Democratic president been able to replace Rehnquist and O’Connor, constitutional law today would be dramatically different. Affirmative action would be on firm constitutional ground. The Voting Rights Act would remain in place. The Second Amendment would protect only the state’s authority to raise militias, not private individuals’ right to own guns. Women’s right to terminate a pregnancy would be robustly protected. The validity of Obamacare would never have been in doubt. Consumers and employees would be able to challenge abusive corporate action in class action lawsuits. And Citizens United v. Federal Election Commission, which struck down regulations on corporate political campaign expenditures and called into question a range of campaign spending rules, would have come out the other way.

But it was not to be. As chief justice, Bush selected Roberts, and as the new associate justice, Samuel Alito. Both were tried-and-true conservatives who had established their reputations in the Reagan administration Justice Department and gone on to serve as federal appellate court judges. Because they replaced two conservative justices, the shift in the Court’s makeup was modest. Roberts was an even trade politically for Rehnquist, for whom he had once served as a law clerk. Alito was much more conservative than O’Connor, who had played the part of swing justice on the Rehnquist Court. But with only four consistent conservatives, the swing justice still controlled outcomes. The principal difference between the Rehnquist and Roberts courts was that Justice Kennedy assumed O’Connor’s role as the Court’s swing vote. Since he is somewhat more conservative than O’Connor, the Court tilted slightly to the right, but only slightly.

President Barack Obama also had the opportunity to fill two vacancies on the Court. He appointed Sonia Sotomayor…