Party voting discipline and the power of parties, legislators and states

We examine the distribution of decision-making power among the principal actors of a federal legislative system; parties, legislators, and constituencies. We are especially interested in how the balance of power between legislators and constituencies depends on the voting discipline exercised by the parties.We derive power measures that are related to the Banzhaf-Coleman index of decision-making power and illustrate with a simple example. Our power measures are novel because they are based on an explicit representation of party voting discipline as well as the structural properties of the decision-making process, whereas previous analyses concentrate on structurally determined power alone.