"Environmental Protection: A Theory of Direct and Indirect Competition for Political Influence", Review of Economic Studies, v72(1), January 2005,  269-286.        

        How is it that environmental groups can have a strong impact on environmental policy but without much lobbying? This paper develops a model of `direct' (lobbying the government) and `indirect' (persuading the public) competition for political influence and finds that they are complementary. However, an increase in the effectiveness of public persuasion, or a rise of public environmental awareness, induces substitution between the two. The findings establish that the empirical phenomenon of lack of political contribution from environmental groups may not be related to financial constraints, but to their greater effectiveness in public persuasion and the growing public environmental awareness.

“ A Model of Substitution of Non-tariff Barriers for Tariffs, ” Canadian Journal of Economics v.33 (4), 2000, pp1069-1090.
   In this paper some coherent explanations are suggested for tariff reductions and substitution of non-tariff barriers for tariffs, taking into account both organized special interests and unorganized consumer interests.  The focus is on how the presence of informed consumers affects the political equilibrium choice of trade policy.  Three effects are identified that interact with each other as an incumbent government substitutes a NTB for a tariff and among other things, it is found that an increase in foreign competition will not cause the government to substitute NTBs for tariffs, but a rise in the government's valuation of political contribution might do so.