Bargaining in Legislatures: An Experimental Investigation of Open versus Closed Amendment Rules

Abstract

We investigate the differential effects of open versus closed amendment rules within the framework of a distributive model of legislative bargaining. The data show that there are longer delays in distributing benefits and a more egalitarian distribution of benefits under the open amendment rule, the proposer gets a larger share of the benefits than coalition members under both rules, and play converges toward minimal winning coalitions under the closed amendment rule. However, there are important quantitative differences between the theoretical model underlying the experiment (Baron and Ferejohn 1989) and data, as the frequency of minimal winning coalitions is much greater under the closed rule (the theory predicts minimal winning coalitions under both rules for our parameter values) and the distribution of benefits between coalition members is much more egalitarian than predicted. The latter are consistent with findings from shrinking pie bilateral bargaining game experiments in economics, to which we relate our results. O ne of the fundamental questions legislatures deal with is how to allocate government resources between constituencies that have different and sometimes conflicting preferences. The formal rules under which this legislative bargaining process takes place are universally recognized to play a major role in the budget allocation process, both within the specialized standing committees assigned to draft legislation and within the parent legislature itself. Although no legislative bargaining model can fully capture the complex nature of this bargaining process, at a minimum it is important to distinguish between situations where a proposal can be amended many times before being brought to a vote (open amendment rule) and situations where the agenda setter exercises greater control and manages to bring unamended proposals to the floor (closed amendment rule). A good deal of theoretical and empirical work has been devoted to understanding the basis for legislatures ceding substantial authority to specialized standing committees and to the impact of the amendment