More on Supreme Court Experience:
My earlier post "The Right Experience for a Supreme Court Justice" drew some interesting comments, and I wanted to follow up. The point of the post was that any person can only have so many experiences. Although it would be nice if inidviduals had a wide range of experiences, life is short and experience can be a bit of a zero-sum game. Asking for a judge with experience A may mean getting a judge without experience B.

  A few commenters weighed in with the point that what matters is experience on the Court as a whole, not for each Justice, and that my post downplayed this point. Here's commenter Prosecutorial Indiscretion:
Your point is well-taken. That said, wanting the Court to involve a breadth of experience does not mean every justice has to have a ridiculously broad background. It just means that, e.g., having one justice who's spent time in the trenches would be nice, so that the Court as a whole would have the benefit of that perspective and experience. Nine justices with antitrust experience would be a bit pointless; one or two seems pretty useful.
  On one hand, it's hard to disagree with this. I think everyone acknowledges that in a perfect world, you would want different Justices to have different experiences. In theory, the Justices with more experience could have an outsized-role in cases for which their experience was relevant, leading to decisionmaking that was better informed. All to the good.

  At the same time, there are two limitations on this that I think are worth noting. First, Supreme Court openings generally occur one at a time. A President normally will not know if there will be any more vacancies in his Term. Creating a group with diverse experiences can work if you are selecting the entire group at once, like college admissions officers creating an entering class with two shortstops, four members of the math club, and two oboe players. But it's a lot harder when a President has only one pick.

  Second, I think it's worth questioning the ideal story of how diverse experiences make a difference at the Supreme Court level. For example, Justice Souter had several years of experience as a state trial judge. Off the top of my head, though, I can't tell how this impacted his work. It's not like I ever expected Justice Souter to have an unusual influence or to bring unusual insights in decisions that involved state court trial proceedings. Justice Blackmun was a math major, but I don't see his opinions in technical or mathematical areas any better than any other Justice. Justice Breyer has the most legislative experience, having worked in the Senate; I don't think his statutory opinions are particularly different than those of any other non-textualist judge.

  In short, it might be that diverse experience leads to better insights, and that candidates with a particular past will be better at certain cases or have a deeper understanding than others. But there's considerable evidence that this often isn't the case, which should temper the focus on particular experiences at least somewhat.