8/9 went to law school at Harvard or Yale (the Notorious R.B.G. went to Columbia Law).
For undergrad, 3 went to Princeton, 1 to Columbia (not RBG, interestingly), 1 to Harvard, 1 to Yale, 1 to Cornell, 1 to Stanford, and 1 to Holy Cross.
That's evidence that signaling matters in a law degree, but the larger context of this discussion is of an undergraduate degree and I don't think the signalling is as strong there.
I agree regarding undergrad mattering less than law school, but as long as we're splitting hairs about RBG, let's split them correctly! =)
She and her husband both went to Harvard Law, though the husband started and graduated one year earlier. He then got a job at a New York law firm and RBG transferred to Columbia to stay near him. She completed her third year at Columbia and received their law degree.
Harvard Law actually has a rule (adopted later) where you can complete your third year elsewhere and still receive a Harvard degree. They offered this degree to RBG, who refused it[1]. So technically you're right that she's a Columbia Law grad, though it's not a stretch to call her a Harvard Law grad as well.