As a side note, you cannot escape values even when you are only considering "free trade". As an example, influential EU law cases include questions of promoting abortion as a freedom of service, ban on Sunday sales, ban on sex dolls ... Then free trade clashes with other fundamental rights, such as a right to strike. Arguably this tension is exactly the spill-over effect that made EU project successful – integration in one area (originally steel and coal for obvious post-WWII reasons) creates pressure in an adjacent area to integrate as well.