Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Kaz Miyagiwa


In the standard common agency model of politics, the interest groups always lobby a single policy-making entity for policy favor. To deal with this unreality, I step in some issues about the trade policy making that is entangled with the multiplicity of public decision-makers. My study cooperates multi-agent and the common agency model to analyze the trade policy making under the political system that is controlled by a number of lawmakers. The analysis points out that the committee of symmetric lawmakers behaves like a single government but the equilibrium policy is not efficient. Because the presence of multiple players on the both sides, lobbies and lawmakers, creates the strategic externalities among lawmakers, it is impossible for all the players to achieve the optimum of their sum bliss. Moreover, focusing on the phenomena of the bipartisan corruption in the United States, I examine the fund-raising race between two parties in the bipartisan political system. If collecting political money implies that the party sells its service to the rent seekers, the party's popularity will fade as its fund raising activity is more vigorous than its opponent's is. The interaction between two political parties is modeled as a differential game. The results show that the subgame perfect equilibrium considerably lifts political money collecting activity compared with time consistent. This partially explains why the political parties ignore the public's criticism on their soft money collecting activities and engage in an ever-escalating fund raising race. Finally, I apply the common agency model and Nash bargaining process to analyze the immigration policy of a small country. Our results show that, under incomplete political economy, the political equilibrium is to set up quantitative restrictions on the inflow of foreign labors. If the marginal cost of deterring illegal immigrants can be covered by the marginal benefit of allowing legal immigrants for entry, setting an optimal border control to deter the illegal immigrants from entry and simultaneously allowing a certain level of legal foreign labor for entry is the political equilibrium. The bargaining power of government does not affect the immigration policy, but in the long run it does.