Justices Stephen Breyer and Antonin Scalia have debated whether U.S. jurisprudence should be cognizant of developments in other countries, as in defining "cruel and unusual". That's a hot issue among some attorneys and even more so on cable news--the conservative types tend to say "no way", while the liberals say: "of course". (Actually, that's way over-simplified and, to a cynical old man, often depends on whose ox is gored. The usual context seems to be social issues: death penalty, etc.)
Now comes a review on H-Net of a book on the Warren Court and its influence on foreign law. (Of course, conservatives might view U.S. law, at least pre-Warren, as a model to be followed, a "city on a hill"; while liberals might be skeptical. Seems that maybe the court's example had an effect, but different in different regions.