In the framework of customary international law, shareholders can claim in its own name when its direct rights was infringed, however, for the loss of value of shareholding in company, shareholder can only be remedied by an indirect way of diplomatic protection. By contrast, in the context of modern international investment arbitration, the arbitral tribunals essentially allow claims by shareholders directly for those reflective loss, due to the lack of corresponding mechanisms in modern investment treaties, the behaviors of arbitral tribunals have attracted many risks, violating the company's creditors and related rights of the interested parties, it is therefore necessary to draw on customary international law and relevant provisions of NAFTA to amend the international investment treaties.