Now this looks interesting:
At last there has appeared a direct and substantial challenge, within the Court, to the constitutional thought of Justice Antonin Scalia, who has long offered an ambitious and forceful account about how to approach the Constitution and laws of the United States. For the next decade, I think, much of the intellectual battle, within the Court and within the nation, will have to be conducted with close reference to the conflict between the starkly different constitutional theories of Scalia and Breyer.
Breyer and Scalia have been at odds for some time now, specifically over the introduction of European jurisprudence in determining American court decisions (Lawrence v. Texas).
Might have to pick this book up. Cass Sunstein is also the author of Republic.com, which was a great read.