The political economy of clean air legislation: An analysis of voting in the U.S. Senate on amendments to the 1990 Clean Air Act

One of the most important functions of a government is to regulate activities which generate negative externalities. Economic theory has a lot to say about the efficient levels of externality controls, but economists have yet to come to a firm consensus on how to privately obtain such levels. 1 Thus, in most situations the government must, through a bureaucratic or legislative process, decide both levels of stringency and implementation strategies for externality regulation. This makes the understanding of how regulatory decisions are made an important issue for study. Much research in political science and economics has attempted to explain voting patterns among members of legislative bodies. In this paper we extend the existing analysis in three ways. First, we address the subject of voting on air quality regulation by the US Senate. A subject of great importance and significance, such votes have not previously been the focus of much empirical investigation. Second, we develop an arguably more correct and effective methodology for measuring and understanding the ideological preferences of individual Senators, as revealed by their voting patterns on 1990 amendments to the Clean Air Act. Third, we apply the minimum chi-square methodology for estimating the determinants of Senator voting patterns on the issue.