Gamson going global? Cabinet proportionality in comparative perspective

We conduct a global, large-N analysis of proportionality in the partisan distribution of cabinet portfolios. Formulated in the context of postwar Western European parliamentary democracy, Gamson's Law predicts that parties joining a coalition government will receive cabinet ministries in direct proportion to the seats they are contributing to the coalition on the floor of the legislature. Using a sample of 1551 country-years of coalitional government in 97 countries from 1966 to 2019, and comparing all main constitutional formats (parliamentary, presidential, and semi-presidential), we find that Gamson's Law does not travel well outside its context of origin. Among the constitutional predictors of cabinet proportionality, we find that pure presidentialism is a major outlier, with an exaggerated form of formateur advantage. Introducing party-system and assembly-level predictors to the debate, we find that party institutionalization tends to increase fairness in portfolio allocation within parliamentary systems only.