Paul F Diehl and Charlotte Ku s new framework for international law divides it into operating and normative systems The authors provide a theory of how these two systems interact which explains how changes in one system precipitate changes and create capacity in the other A punctuated equilibrium theory of system evolution drawn from studies of biology and public policy studies provides the basis for delineating the conditions for change and helps explain a pattern of international legal change that is often infrequent and sub optimal but still influential
