This is also the most conservative Court since the New Deal. In a widely cited 2009 study, conservative judge and scholar Richard Posner, as well as his colleague at the University of Chicago law school William Landes, ranked the ideology of 43 Supreme Court justices from 1937 to 2006. Four of the five most conservative judges served on the Court that year. None of the five most liberal judges did. Ruth Bader Ginsburg was the only current judge to rank among the 10 most liberal justices.
Posner and Landes also found that the more ideologically polarized the Court was, meaning the greater its range from right to left, the greater the number of cases decided by one vote. It found, critically, that ideology "matters more in the Supreme Court than in the court of appeals."
There have not only been more ideologically sorted rulings in recent decades. The most significant laws are increasingly decided by the same one-vote margin that undermines the very "supreme" authority of the Court. The 1966 Miranda decision, which defined police suspects' rights, was an early signal that 5-to-4 rulings were going to shape this nation like never before. The 2000 Bush v. Gore was decided along the same narrow margin.
In the Roberts Court, 5-to-4 majorities have allowed unlimited corporate and union campaign spending, upheld an individual's right to gun ownership, limited an employee's ability to file a pay discrimination, decided states cannot impose mandatory life sentences on juvenile murderers without the possibility of parole, and limited class-action suits as well as decided the constitutionality of the health-care law.
This polarization has not gone unnoticed. The judiciary remains the most trusted branch of government. Sixty-three percent of Americans said in autumn 2011 that they have a "great deal" or a "fair amount" of faith in it. Yet that is the lowest share to express trust in the judicial branch since 1976, when Gallup first asked the question.
And the Supreme Court is especially sullied. Prior to Thursday's decision, about three in four Americans agreed that "personal or political views influence" current Court decisions, according to a recent New York Times/CBS News Poll. Yet the public has not seen the Court as apolitical since, at least, it became more politically ordered. In 1946, a narrow plurality, four in 10 Americans, told Gallup that they "agree" that "the Supreme Court decides many questions largely on the basis of politics."
This year's term saw roughly as many 5-to-4 rulings as 1946. But then it was not the norm. In 1941, for the first time, at least a tenth of the Court's opinions were decided by this narrow margin. The rate of these minimum majority decisions has not fallen below 15 percent since 1991. Some modern Court years are more partisan than others. But the upward trend remains steady since the mid-twentieth century.
So liberals celebrate a rare 5-to-4 decision that went their way on the Roberts Court. Conservatives rue the ruling. Polarization, however, endures. The four liberal justices lined up as predicted. Three of the four most conservative justices also fell in line on the greatest issue before the Court. All the conservative judges agreed on other aspects of the ruling. The swing vote was a surprise on the headline decision. But the Supreme Court remains generally sorted along partisan lines. And it's not news. Rather, it's old news. That's how accustomed to polarization we've become. Or how cynical.