Adam Liptak has an excellent story about the latest empirical study on the ideological direction of the Supreme Court. The results are not surprising:
In its first five years, the Roberts court issued conservative decisions 58 percent of the time. And in the term ending a year ago, the rate rose to 65 percent, the highest number in any year since at least 1953.
Four of the six most conservative justices of the 44 who have sat on the court since 1937 are serving now: Chief Justice Roberts and Justices Alito, Antonin Scalia and, most conservative of all, Clarence Thomas. (The other two were Chief Justices Burger and Rehnquist.) Justice Anthony M. Kennedy, the swing justice on the current court, is in the top 10.
As I've said before, if anything, this data underestimates the Court's shift to the right. Warren Burger, in these studies is counted as just as conservative as Scalia and Alito. But the coding of votes is generally relative; what looks "conservative" or "liberal" will depend on what kind of cases the Court takes and how other justices vote. For much of Burger's tenure, the liberal votes on the Court were considerably more liberal than Anthony Kennedy. Burger -- who, for example, joined the majority in Roe v. Wade -- may well look more like Kennedy if he sat on today's Court.
It's also worth noting that the Roberts Court, while more conservative than any Court in more than 5 years, is certainly not more "restrained" in any non-tautological sense than the Warren Court. It doesn't strike down statutes or overrule precedents any less (or any more) than its more liberal predecessors. It's an activist Court; it just uses its activism to different ends, most notably to favor the state over the individual in criminal cases and corporations over individuals in business cases. Whether a judicial review that consistently favors interests that are already overrepresented in ordinary political processes is a good thing I'll leave for you to judge.