Do (did) all supreme court appointees have to be judges?

Fair clarification, Cliffy -

OxyMoron, Esq.

Felix Frankfurter was born in Austria-Hungary.

Who should not, under any circumstances, be confused with Justice Frank N. Furter. The less said about that whole sorry episode of our judicial history, the better.

Yeah, but Tim Curry was brilliant in the biopic.

–Cliffy

Not to turn that into a Great Debate, but I wouldn’t call that a “stupid practice” (and not a predominantly European one, either). If the appointed/elected person is citizen of the country in question, I think that is sufficient to ensure he’s fulfilling the duties of the office with due care. I would even argue that naturalized citizens might in some cases be more apt than native born ones, as they had to somewhat struggle, at least undergo a certain procedure, to obtain citizenship, and might therefore value it higher. But that’s just IMHO.