Chart of the Day: The Supreme Court Over the Past 70 Years

Christopher Ingraham at Wonkblog pointed me to an interesting bit of data yesterday. It’s the Martin-Quinn measure of how the Supreme Court tilts over time, and apparently it’s widely accepted as reasonably accurate. Here it is for the entire postwar period:

There are two fascinating nuggets here:

  • Despite conservative kvetching, the Court has leaned conservative for all but seven years from 1946 to 2013. The seven years of the Warren Court are literally the only period in recent history during which the Court has been consistently liberal.
  • The Martin-Quinn measure depends on the votes of the median judge, which is Anthony Kennedy right now. This is what accounts for the Court’s recent shift to the left. According to his Martin-Quinn score, Kennedy has been getting steadily less conservative ever since he joined the Court, and over the past three years he’s become positively liberal:

I suppose this is old news to veteran court watchers, but it’s new to me. Has Kennedy really shifted that much over his career? And is he now generally left of center? If so, does this have anything to do with the effect of Sotomayor and Kagan joining the Court in 2009-10? It sure looks like it.