PCB is a toxic chemical used in electrical equipment that biodegrades slowly. Since the 1970s, international regulations on PCBs have tightened. In 1990, Canada banned the export of PCB waste, except to the U.S. with EPA consent. In 1995, the EPA reversed its closed-border policy, allowing PCB waste imports under discretionary exemptions. In response, Canada issued the PCB Waste Export Interim Order, restricting exports except for U.S. agencies in Canada with EPA consent. In 1997, a regulatory amendment reopened the border, but a judicial decision later closed it again. SDMI argued that the export ban harmed its business and violated NAFTA obligations.