Lobbying and Information Transmission in Customs Unions

This paper studies a customs union agreement when governments are subject to the pressure of special interest groups that have better information about the competitiveness of the industries they represent. We focus on the agreement’s effect on the structure of political influence. When joining a customs union, the structure of political pressure changes and with privately informed lobbies, a new effect emerges: the governments can use the information they learn from the lobby of one country to extract rents from the lobbies of the other country. We call this the “information transmission effect”. This effect enhances the governments’ bargaining power in a customs union and makes lobbies demand less protection. Thus, we find that information transmission increases the welfare of the agreement and decreases tariffs towards non-members. We also investigate the incentives for the creation of a customs union and find that information transmission makes such agreement more likely to be politically sustainable.