Whose Law is It? Network Analysis of the Evolution of U.s. Environmental Law, 1973-2013

Abstract: Laws – be they common law, statutes or the constitution itself – evolve continuously. People make use of them, and discovering ambiguities or disagreeing on their proper application, ask courts through- out the nation to re-interpret them. What are the political drivers of this process? This paper analyzes a dataset of over 10000 U.S. environmental court cases, reconstructing the network of citations to legal precedent for a period of forty years. This dynamic network provides full information about the use of precedent over time and whether precedent is affirmed or undermined by written opinions. The network is thus a reflection of the evolution of the legal rules of environmental governance in the United States. The paper introduces multiple statistics that capture dynamic features of this network. These statistics are designed to capture significant changes in the content of the law. Using these measures, the analysis tests whether legal change is affected by changes in the preferences of pivotal legislators. Overall, the dynamic properties of this network reveal that laws evolve largely independently from shifts in legislative power.