In investment treaties, the self-judging security exception clause allows states to restrict the exercise of investors’ rights and protections provided for by such treaties during security emergencies. During the last decade, such a clause has been included in numerous investment treaties to support state positions vis-à-vis foreign investors. States consider that this provision gives them a very broad discretion to limit or derogate from obligations which arise under the treaty. In this article, after having identified the self-judging character of this clause, it will be demonstrated that such a clause does not affect the jurisdiction of the tribunal but requires the tribunal to apply the principle of good faith as the proper standard of review to interpret the elements of the clause, preventing states’ abuse of such a clause.