This paper investigates variation in the design of labor provisions in preferential trade agreements (PTAs) by focusing on the role of domestic interest groups and government partisanship. Specifically, it asks whether left-leaning governments and strong trade unions are associated with more, and more far-reaching labor provisions in PTAs. We do not expect left governments to be more likely to promote labor provisions of any type than right governments because labor provisions in PTAs have become more of an issue for human rights championing and one that is used also by right-leaning governments because they are becoming unobjectionable rights, but also to win over majority if that is required for signing the agreements. By contrast, we expect strong, encompassing trade unions to be associated with more and stronger labor provisions in trade agreements. Specifically, as the historical and contemporary champions of the promotion of labor rights, trade unions are expected to push for and obtain the adoption of ILO instruments combined with binding language and/or their enforceability. We test these hypotheses relying on an original dataset of labor provisions included in 500 PTAs signed between 1990 and 2014. This dataset covers 154 different labor provisions that relate to five overarching dimensions, namely substance (i.e., references to substantive labor provisions), obligation (binding commitments over substantive labor provisions), enforceability, cooperation, and institution (i.e., the setting-up of specific committees for the purpose of reviewing or monitoring the implementation of the agreement). The paper has implications for the literatures on the power of trade unions and the design of PTAs.
