A common perception is that since the Supreme Court frequently divides 5-4, it is balanced between conservatives and liberals. The vote breakdown, however, does not tell us anything about the Court's ideological breakdown. The Supreme Court has discretionary jurisdiction, and any group of nine justices will tend to choose cases that divide them because those cases are the ones that are the most legally uncertain.
On April 14, 2009, Professor Geoffrey Stone presented a talk in the Chicago's Best Ideas lecture series entitled "Obama's Supreme Court." He discussed what he thinks the makeup of the current Court really is. (Throwing the word "Obama" in the title is a good way to get people in the door.) In a series of entries on Huffington Post, he describes what follows in more depth.
First, Professor Stone served up some facts about the current Court. Seven of the nine sitting Justices were appointed by Republicans, as were twelve of the last fourteen appointees. The so-called "swing" vote on the Court has shifted from Justice Stewart to Powell to O'Connor to Kennedy, each of whom is widely considered more conservative than the last. According to an article by Professor Landes and Judge Posner, four of the current Justices are more conservative than any Justice since 1937 except Rehnquist. Finally, there are not any "full-throated" liberals like Justice Marshall or Brennan on the Court.