Interest groups and policy volatility

We offer a model of how interest groups affect policy stability. The relationship between interest group density and policy volatility is concave because of two forces: (a) the number and interaction of interest groups in a policy domain and (b) the effect of this interaction on policy image and attention. After laying out the logics of both processes, we identify three ideal type situations: (a) capture (low interest group density, low attention) and (b) deadlock (high interest group density, high attention) lead to low levels of policy volatility while (c) lability (medium interest group density, intermittent attention) leads to high levels of policy volatility. For our empirical evidence, we rely on all budget functions in the American states from 1984 to 2010 and employ generalized additive regression modeling. The article contributes to the literature on understanding interest group strategies, interest group influence in policy making, and broader questions of deliberative democracy.