Marcelo has a new NBER paper, jointly with Gawande and Krishna, on "What governments maximize and why: the view form trade". The idea is that tariffs, set in political-economic equilibrium, depend on import demand elasticities and output-to-import ratios in each sector. The Grossman-Helpman (1994) setting provides an explicit relationship between tariffs and these measurable variables that is used to estimate the relative weight that a government places on welfare versus contributions.
So, they first calculate this trade-off parameter and then regress it on a bunch of political and society indicators and find that checks and balances embedded in the decision making process cause more welfare minded governments and so do more informed voters, as measured by literacy and the degree of urbanization. More interstingly, the more ideologically attached are voters to parties and the greater the productivity of the media in influencing uninformed voters, the less weight governments put on social welfare when making trade policy.
JD is skeptical and explains why here. I still find it intersting that the Spearman rank correlation between Transparency International Corruption Perception Index and an index built from import demand elasticities and output-to-import ratios is 0.67!