In international investment law, the principle of legitimate expectations is a praetorian creation: to interpret one of the — laconic — standards of investment protection, the standard of fair and equitable treatment, arbitral tribunals referred to the legitimate expectations of the investors, elevating them to the rank of criterion of the said standard. There is a frustration of the legitimate expectations of investors — and a breach of fair and equitable treatment —, where the host State does not respect a promise made to the investor who, on this basis, made its decision to invest. The arbitral tribunal in the case of Parkerings v. Lithuania [ICSID No. ARB/05/8, award (11/09/2007)] explained the principle of legitimate expectations in the following way: "The expectation is legitimate if the investor received an explicit promise or guarantee from the host-State, or if implicitly the host-State made assurances or representation that the investor took into account in making the investment. Finally, in the situation where the host-State made no assurance or representation, the circumstances surrounding the conclusion of the agreement are decisive to determine if the expectation of the investor was legitimate. In order to determine the legitimate expectation of an investor, it is also necessary to analyse the conduct of the State at the time of the investment." In CSR matters, the principle of legitimate expectations may be used as an instrument of dispute, in order to decide whether compensation is really due to an investor who brings such a claim. In this regard, the legitimacy of the expectation would be measured according to the breaches by the host State, but also according to those of the investor.