You are missing something: the NAFTA chapter 11 experience. Take the S.D. Myers case, where Canada banned the cross-border transport of toxic waste, or the metal-clad case in Mexico, where the Mexican state regulated to control the siting of a toxic waste dump, and many other issues.
Almost half of the NAFTA investor state claims dealt with environmental protection. It's not simply an issue of the object of the policy, whether it's market-protecting or environment- protecting. It actually goes beyond that. The arbitral tribunals have looked at issues of indirect expropriation. These are the types of issues that are being adjudicated by these tribunals.