Amplifying public opinion: The policy impact of the US environmental movement

Time-series data from 1960-1998 is used to test hypotheses regarding the impact of protest and public opinion on the passage of U.S. environmental legislation. An amplification model of policy impact is introduced which posits that protest affects legislative action independent of public opinion as suggested by protest event theorists, whereas the impact of public opinion on legislative action is greater depending on the level of protest. Evidence is found for the existence Of an amplification mechanism between environmental movement protest and public opinion, where public opinion affects policy above and beyond its independent effect when protest raises the salience of the issue to legislators. These findings point to the need to restructure analyses of the impact of social movements on public policy.