The full quote from which the tagline is taken is:
“Law reflects, but in no sense determines the moral worth of a society…. The better the society, the less law there will be. In Heaven, there will be no law, and the lion will lie down with the lamb…. The worse the society, the more law there will be. In Hell, there will be nothing but law, and due process will be meticulously observed.”
It comes from a lecture by Prof. Grant Gilmore, published as The Ages of American Law (New Haven: Yale University Press, 1977), pp. 110-111.