Chapter 11 of NAFTA allows Transnational corporations to sue a national or regional government if the corporation feels that laws inacted by the government are "a barrier to trade". A tribunal was created by the members of NAFTA (Canada, United States, and México) to review the complaints of the corporations. Under NAFTA, arbitration tribunals are modeled after private commercial arbitrations: they are held behind closed doors, with no avenues for the public to participate and observe. Some recent examples of the decisions made by the tribunal are:
ETHYL: This is an American company located in Virginia. It manufactures a product called methylcyclopentadienyl manganese tricarbonyl also known as MMT. Canada banned the use of MMT in fuel due to health reasons. Ethyl took the Canadian government to the tribunal and in 1997 Canada was forced to lift the ban and pay $21 million to Ethyl.
METHANEX: This Canadian company produces methyl tertiary butyl ether also called MTBE. California Governor Gray Davis ordered that the use be MTBE be phased out by 2003 after studies showed that the additive may cause cancer as well as neurological, dermatological and other problems in humans, and is spread through the water system of California. The tribunal ruled that California's Environmental law violates NAFTA and so the state has been ordered to lift the ban (which it has done) and pay the corporation $900 million (which it has not done).
Bear in mind the money that the governments must pay to the corporations is taken from tax revenues, and the public will never learn of these cases unless more are leaked to the independent media.