One answer (there are many others) is that the Justices are constrained by internal and external legal cultures. The internal legal culture is inescapably inside the heads of the Justices. The Justices are lawyers, trained in a particular tradition. The internal legal culture has its own powerful symbols, its own language and etiquette; and the Justices operate in this context. Of course, each Justice is an individual man or woman; each has his or her own take on the internal legal culture. But this culture sets boundaries and limits within which the Court, of necessity, does its work.