Handbook of the International Political Economy of Migration, Chapter 12:

Rather unnoticed by academic debates, a dynamic agenda on trade-related mobility rights has taken shape that sits at the nexus of liberal political economy and the regulation of one of the most sensitive matters of state sovereignty. The door to this agenda was opened in 1995 with the inclusion of so-called “mode 4” mobility of natural persons in the General Agreement on Trade in Services (GATS) of the WTO. Whereas current GATS mode 4 commitments are quite limited, this chapter shows that recent initiatives and particularly regional and bilateral Free Trade Agreements (FTAs) gradually expand these clauses beyond the former trade hegemons' original intentions.