Disclaimer. Don't rely on these old notes in lieu of reading the literature, but they can jog your memory. As a grad student long ago, my peers and I collaborated to write and exchange summaries of political science research. I posted them to a wiki-style website. "Wikisum" is now dead but archived here. I cannot vouch for these notes' accuracy, nor can I even say who wrote them. If you have more recent summaries to add to this collection, send them my way I guess. Sorry for the ads; they cover the costs of keeping this online.
Strom. 2001. Agency and Parliamentary Democracy. in Delegation and accountability in parliamentary democracies. Strom, Muller, and Bergman, eds. Oxford: Oxford University Press.
Using principal-agent theory, Strom examines the ways in which principals control their agents in parliamentary systems. Because the nature of this regime-type means that a single principal delegates to a single agent (or to non-competing agents), and a single agent is responsible to a single principal, ex post controls are less effective (i.e. problems with hidden information and hidden action are more likely to arise since no comparisons across agents are possible). Instead, ex ante controls are put into place to make ex post controls less necessary. These controls include an intense screening process (climbing the party ladder) and a contract design that ensures that agents' interests are highly compatible with their principals.
Strom analyzes differences between delegation in parliamentary and presidential regimes, concluding that presidential regimes are more reliant on ex post controls for preventing agency loss, while parliamentary regimes more reliant on ex ante controls. In a presidential regime, you might elect a dunce (an "outsider"), but you'll have good institutional checks (ex post controls) on his actions; in a parliamentary regime, MPs are thoroughly screened before becoming Prime Minister (ex ante controls), but you have fewer institutional checks incase the PM turns out to be a doofus later.
For a very similar argument, see also Strom (2000), "Delegation and accountability in parliamentary democracies."
Agency loss refers to the general problems that arise from delegation. It has two types:
Following Kiewiet and McCubbins (1991), Strom notes two general ways to combat agency loss: ex ante (before) and ex post (after).
Ex Ante Controls:
Ex Post Controls:
Parliamentary institutions favor ex ante controls over ex post controls:
Presidential systems favor ex post instruments:
Bottom line: the advantages of having a parliamentary system is efficiency, while the disadvantage is lack of transparency. Given the sacrifice of ex post control mechanisms for limiting agency loss, ex ante mechanisms are abundant and strong in this type of system.
Research by the same authors
Research on similar subjects