Cass Sunstein has a problem if he wants to get on the Supreme Court. It’s not his intellect or credentials. According to Elena Kagan, also a contender for the high court, “Cass Sunstein is the pre-eminent legal scholar of our time — the most wide-ranging, the most prolific, the most cited, and the most influential.”

A shoe-in shoo-in for the Court? Maybe, but maybe not now. The reason? It is not clear which “seat” he would fill. Perhaps recognizing the problem, Sunstein argues for “intellectual diversity” rather than diversity based on demographics:

The question of diversity on the Supreme Court has been with us for a long time. In the past, there was a de facto “Jewish seat” on the Supreme Court, first filled by Louis Brandeis and then for many years by Felix Frankfurter, who was succeeded by Arthur Goldberg, followed in turn by Abe Fortas. (Justices Ruth Bader Ginsburg and Stephen Breyer are both Jewish.) There is, in effect, an African American seat today. Thurgood Marshall was replaced by Clarence Thomas and, unless another African American is named to the court first, when Thomas leaves he will almost surely be replaced by an African American….

Unfortunately, all this focus on demographics misses the most important point. What the court most needs is intellectual diversity. It should have people with a range of perspectives, different kinds of knowledge and different points of view. For many questions that come before the court, expertise is important, and it is impossible for anyone to be an expert in everything. The court has greatly benefited from having Breyer, a specialist in copyright law, and Justice Antonin Scalia, a specialist in separation of powers. And for the most important questions, internal differences are crucial because they sharpen arguments and increase the likelihood that the court will get it right.

Sunstein’s argument is not a self-serving attempt to get Obama’s nomination. The argument quoted above was made with regard to George Bush’s nomination of John Roberts in 2005. But the point remains true to this day. It is unclear which “seat” Sunstein would fill, particularly if new seats are assigned based on race, gender or ethnicity.

But it is clear that Sunstein would fill an intellectual seat and be a formidable voice on the Court to rival John Roberts. That may not be enough.

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