When the NAFTA was negotiated and signed, Canadians were basically told--if they were told anything--that investor state arbitration in chapter 11 of the NAFTA was needed because of structural problems of corruption in the Mexican court system, and it wasn't really an issue that should concern Canadians. Since then the international trade bar and others have very aggressively used those provisions to challenge Canada--and too many times successfully. There have been 30 investor state claims.
I think there's growing awareness in Europe of the hazards to environmental protection regulation with these types of rules. Canada and Europe have highly regarded democratic systems of justice that are open to everyone, including corporations. I don't really believe that the risk of entrenching this investor state arbitration system, which would be new for Europe in a regional trade agreement, is an appropriate one.