The issue of recognition of contractual rights as protected investments in international investment arbitration, primarily under the auspices of ICSID, has sparked divergent approaches in case law. Treatment of certain contracts and the criteria used differ, which leads to unwelcome consequence of lowering legal certainty in a very sensitive issue. The aim of this paper is to contribute to enhancement and clarification of legal reasoning in this area, with a special focus on the criteria to be used and on sales contracts which are particularly controversial in practice. This is done through the analysis of the current state of affairs which is followed by a proposition of a new model of criteria which could present a beneficial compromise between the existing models and increase certainty.