It is well-established that presidential democracies fail more frequently than parliamentary democracies, but there is little consensus on why. We argue that the threat of regime failure changes the composition of executive-legislative bargains more in presidential regimes than in parliamentary ones. Presidents, therefore, have a greater incentive to raise the spectre of regime failure than prime ministers. We conjecture that presidents can do this through the commission of human rights abuses. Since this strategy is also aimed at manipulating executive-legislative bargains, it will not result in regime failure if actors acquiesce to preserve the regime. However, legislators may suspect that the president is being strategic and fail to acquiesce. Either way, the increase in human rights abuses may escalate, triggering extra-constitutional behaviour from third parties. We find evidence that human rights abuses are much more common in presidential than in parliamentary democracies. Indeed, there is no robust evidence that presidential regimes have, on average, better human rights records than authoritarian regimes. We also find that human rights abuses are associated with democratic breakdown and that, once we control for human rights abuses, presidential regimes are no more likely than parliamentary regimes to experience regime failure. These findings support the theory developed in our study, helping to explain why little evidence exists for otherwise logically compelling theories of the fragility of presidential democracy.

Thiago N. Silva is a Lecturer in the School of Politics and International Relations and Deputy Director of the Australian Centre for Federalism at the Australian National University. His research focuses on comparative politics, with an emphasis on political institutions and political economy. Thiago's research projects have addressed the dynamics of coalition governments and policy-making processes in presidential and parliamentary democracies. In his recent research, Thiago also examines the consequences of coalition governments on voter behaviour and party competition and the consequences of human rights abuses on democratic breakdown. His work has been published or is forthcoming in leading political science journals, including the American Political Science Review, the Journal of Politics, the European Journal of Political Research, Political Science Research and Methods, Legislative Studies Quarterly, the Sage Handbook of Political Behaviour, and others.