http://www.slate.com/articles/news_and_politics/politics/2015/06/john_roberts_isn_t_a_reliable_conservative_vote_the_chief_justice_is_siding.html

John Roberts has changed. Consider the chief justice’s voting record. From 2005—the year he was appointed—until 2012—the year of the first Affordable Care Act decision—Roberts was a reliable vote on the court’s staunch conservative wing. In controversies from abortion to campaign finance to guns, Roberts sided with Justices Antonin Scalia, Clarence Thomas, Samuel Alito, and Anthony Kennedy. The 2012 health care case was the first time Roberts had ever voted with the liberal side of the court in a 5–4 decision. Lately, however, we’re seeing a very different Roberts. Last term Roberts surprised many by breaking left on a few major cases. And so far this term, Roberts has voted with Stephen Breyer (90 percent), Ruth Bader Ginsburg (85 percent), and Sonia Sotomayor (83 percent) more often than he has joined Thomas (66 percent), Kennedy (74 percent), and Alito (77 percent). And that isn’t just on minor cases. He’s recently sided with the liberals in cases on issues that typically divide the court along ideological lines, including campaign finance and anti-discrimination law.