Adam Liptak notes an interesting talk John Roberts gave a few weeks back about the importance of Supreme Court justices having prior judicial experience:
As late as 1972, when Chief Justice Roberts’s predecessor, William H. Rehnquist, joined the court as an associate justice, former federal judges were in the minority.
As a consequence, Chief Justice Roberts said, “the practice of constitutional law — how constitutional law was made — was more fluid and wide ranging than it is today, more in the realm of political science.”
Since then, Chief Justice Roberts continued, “the method of analysis and argument shifted to the more solid grounds of legal arguments. What are the texts of the statutes involved? What precedents control?”
That move, he said, has resulted in “a more legal perspective and less of a policy perspective.”
Liptak points to a good bit of academic literature that rejects "the norm of prior judicial experience." But it's the political ramifications of Roberts's remarks that are most significant, since I'm sure Senate Republicans will point to them as a litmus test of sorts if/when Obama nominates anyone to the Court. The good news for Obama is that the people thought to be at the top of his list of potential nominees include current federal judges, such as Diane Wood and Sonia Sotomayor, so that's a litmus test they could easily pass. Of course, because that's the case, I'd imagine the Senate GOP---perhaps aided by Ken Starr--will be coming up with some other litmus tests.