Studying the member states' constitutional choice of European decision rules most power index analyses concentrate on the relative decisiveness of member states in the Council of Minister. However, this emphasis has two shortcomings: First, it ignores the interaction between the Commission, the Council of Ministers and the European Parliament which provides multi-cameral decision making for European legislation. Second, although relative decisiveness is applied to the measurement of the member states' (expected) distribution of legislative gains, it does not take into account the member states' expectation of the extent of gains depending on their absolute inclusiveness. In this article we present a model of member states' constitutional choice of European decision rules with regard to the two notions of power: actors' relative decisiveness and their absolute inclusiveness in decision making. We present an index to measure inclusiveness and we apply our concept to European multi-cameral procedures. Hereby, we give an account for the member states' recent reforms of legislative procedures.