As global economic integration intensifies and transnational investment conflicts proliferate, host states often face difficulties in protecting public interests in crises. This Article compares the two major defenses commonly used by host states-Necessity in customary international law and the Essential Security Exception Clause (ESEC) in Investment treaties. Necessity demonstrates an extremely low success rate in practice, attributable to its stringent substantive requirements and onerous evidentiary burden. ESEC, with its self-judgment wording of "it thinks it is necessary", gives the host country greater discretion and gives priority to the application according to the principle of special law. In recent years, the success rate of defense has exceeded 70%, and many countries have been recognized for citing its restrictions on foreign investment in the medical field during the epidemic. This change highlights that international investment law is evolving from abstract customary rules to special treaty provisions, which can better adapt to new challenges such as epidemics and economic crises and balance public interests and investment protection.
Feng Shi (Tue,) studied this question.