Does Separation of Powers Promote Stability and Moderation?

It is often asserted that separation of legislative powers tends to make legislation both more moderate (because concessions to all veto players are needed to secure enactment) and less frequent (because sufficient concessions are sometimes infeasible). The formal analysis in this article shows this claim to be incomplete and sometimes incorrect. Although greater separation of powers makes legislation more difficult to enact, it also makes legislation, once enacted, more difficult to repeal. Attenuating the threat of repeal means that when one faction has sufficient power to push through extreme policies, it is more likely to do so than would be the case if legislative power were more concentrated. These two effects cut in opposite directions, and it is difficult to say, as a general matter, which will predominate. Indeed, increasing the fragmentation of legislative power may sometimes increase both the expected frequency and the expected extremism of legislative enactments.