Multinational corporations are operating across international borders with ever-greater ease and very few restrictions. Progressive lowering of barriers to international trade, investment and financial flows; the proliferation of investment treaties; and the now endemic use of investor protection provisions in trade agreements has given companies powerful tools to avoid accountability for foreign actions and to undermine the legitimate public interest policies of States and communities. By contrast, the tools available to address the transboundary harms caused by corporate activities remain limited, weak, slow, and difficult to access. CIEL explores and develops new legal tools to counterbalance the power of multinational corporations and increase transboundary corporate accountability. High among those is our work to strengthen extra-territorial human rights obligations of States in order to hold States accountable for transboundary and global damage.