Promotion of the “rule of law” is a strong argument in favour of international investment law. This chapter addresses the actual and potential role of rule of law criteria for investment tribunals in three areas: whether measures taken by domestic courts constitute expropriation, a denial of justice or a violation of the effective means standard. It demonstrates that rule of law criteria were often the decisive standard in examining judicial decisions of national courts although many of the investment tribunals did not refer to the concept of the rule of law explicitly. Rule of law criteria can serve as a useful toolbox for investment tribunals when dealing with alleged denials of justice, judicial expropriation and violations of the effective means standards. The rule of law standards used by investment tribunals are fairly similar to the requirements of human rights treaties and those developed in the case law of the European Court of Human Rights in the context of rule of law and judicial proceedings. So far, investment tribunals have not made explicit reference to the concept of the rule of law to justify the criteria they apply when assessing measures of domestic courts. An explicit linkage to the concept of the rule of law could give these criteria additional authority and highlight their importance.