Why was a new person selected for the position of US Chief Justice?

Question

The last turn over of the position of Chief Justice, was from Burger to Rehnquist, and at the time, Rehnquist was already on the Supreme court as an associate justice.

Why then, this past year, was a completely new person selected for the position of Chief Justice? (John Roberts)

Would it not make sense to give the position of Chief Justice to an already experienced Justice, and a new justice replace him or her as an associate?

I'm not quite sure how the law of selecting a Chief Justice works, and why they would choose a completely new person this time, to head up the Supreme Court.

Answer 1

Looking at the makeup of the Supreme Court, I think it was to ensure that the Chief Justice would be a Republican appointee for a long time. All of the other are either Democratic appointees (Breyer, Ginsburg), rather liberal (Souter, Kennedy, Stevens) or would have difficulty getting approved by the Senate as Chief (Thomas). That leaves Scalia, but he was almost 70 at the time, and likely could not be counted on to stay on the court for more than 5-10 years. Roberts, on the other hand, was a spry 50 years old and thus will likely lead the court for at least 20 years.

Answer 2

There is no "law" about selecting a Chief Justice. The President can appoint anyone whom he chooses and who will be confirmed by the Senate. And as the guy above said, most Chiefs did not have previous service on the Supreme Court as associate Justices. There have even been Chief Justices who had never been judges at all before -- most notably Earl Warren.

Answer 3

More often than not, the new Chief Justice had not served on the Supreme Court.