Haven't read it yet, but lawprof Eric A. Posner has posted what looks like an interesting article on SSRN, The Constitution of the Roman Republic: A Political Economy Perspective:
The constitution of the Roman Republic featured a system of checks and balances that would eventually influence the American founders, yet it had very different characteristics from the system of separation of powers that the founders created. The Roman senate gave advice but did not legislate; the people voted directly on bills and appointments in popular assemblies; and a group of magistrates, led by a pair of consuls, proposed bills, brought prosecutions, served as judges, led military forces, and performed other governmental functions. This paper analyzes the Roman constitution from the perspective of agency theory, and argues that the extensive checks and balances, which were intended to prevent the recurrence of monarchy, may have gone too far. Suitable for an earlier period in which the population was small and the political class was homogeneous, the constitution proved unworkable when Rome acquired a vast, diverse empire. The lessons of Roman constitutionalism for the American constitution are also discussed.
Eric makes many interesting points, and I learned a lot from the paper. But I disagree with the bottom-line conclusion that the Roman Republic failed because it had too many checks and balances, which led to paralysis and gridlock. Even in its last, most dysfunctional century, the Republic repeatedly vanquished powerful foes, including monarchs such as Mithridates of Pontus, Eric’s argument that monarchy was a more efficient form of government during this period notwithstanding. The Republic also undertook various important new domestic policy initiatives, including expanding the citizenship and granting land to enormous numbers of military veterans. This is not the sign of a polity paralyzed by gridlock.
On balance, I tend to agree with the more conventional view that the Republic failed not because of gridlock, but because of agency problems: the Senate and people gradually lost control of the larger and larger military forces needed to defend their growing empire. These forces were increasingly more loyal to their immediate commanders than to the state. As a result, unscrupulous generals such as Marius, Sulla, and ultimately Caesar could use “their” troops to seize power. This problem probably could not be easily solved in a large empire during an era when communications were difficult and slow and the central government could not readily control far-flung standing armies. Indeed, the same problem eventually played a decisive role in bringing down the empire that replaced the republic.