Generous legislators?: a description of vote trading agreements (theory and experiments)

Legislators trade influence to attain approval of their most preferred bills. The classical example is found in pork barrel politics with concentrated benefits and diffuse costs where logrolling agreements involving two (or more) legislators can load costs onto legislators excluded from the winning coalition. As Ferejohn et al (1987) show, the cheapest of these outcomes is the only agenda independent one. We model the bargaining game amongst legislators and show that this outcome can be supported by some specification of legislator preferences, but we shed light on a different outcome that has so far been overlooked in the literature: we may observe that legislators most affected by logrolling agreements (those who bear costs with no benefit) may break such coalitions. Specifically, in equilibrium some legislators ‘generously’ offer their support for some bills that are not to their benefit, and obtain NOTHING in exchange. We report evidence from experimental tests in which our theory predicts 2/3 of the subjects’ behaviour.