The growing concern of States in order to attract foreign investment into their territories has led to the formulation of a legal structure aimed at encouraging investment through the granting of a secure and stable environment for the investor in the host State. In the core of this structure is the fair and equitable treatment standard which, as a non - contingent standard, constitutes an independent and reliable system for the protection of the investor. However, the application of the true fairness concept underlying the standard seems at times in jeopardy, due to a serious lack of precision regarding its true meaning.  Arbitrators and scholars have wandered from one interpretation to another, trying in occasions to fit the standard in existing legal concepts such as the international minimum standard of customary  international law or simply creating a whole new meaning by means of self-contained legal figure. The article examines the latest and most decisive attempts to define the standard within modern international law, all of which have contributed to a dynamic but controversial discussion around the topic.