Fair and equitable treatment is a central standard in international investment law. This standard is included in the vast majority of international investment agreements as one of the most important standards for the protection of foreign investors. Historically, international investment agreements contained short and general fair and equitable treatment clauses, formulated either as independent provisions, in reference to general international law or the minimum international standard of customary international law. It is especially since the first decade of the 21st century that the formulations of fair and equitable treatment have become complex and sophisticated clauses that are increasingly diverse and produced, which have sought to address the different elements of the standard that have developed over time. Editorial approaches reflect long-standing controversies over fair and equitable treatment and whether this concept should be developed according to international minimum standards or as an independent and consistent standard that could go beyond customary international law. Both terms have remained vague and have difficulty interpreting fair and equitable treatment which, because of its general nature, has become an important means of redress in investor-state arbitration. The evolution of arbitration has stimulated the emergence of various elements of fair and equitable treatment, including the protection of legitimate investor expectations, protection from discrimination and arbitrary treatment, as well as the principles of ordinary procedure, denial of justice and transparency. The growing number of cases on the basis of fair and equitable treatment has also raised concerns and criticism that a broad approach to the standard would threaten the sovereignty of host countries and their right to regulation, as well as the principle of sustainable development. These concerns and the fact that an increasing number of investment disputes have been initiated against developed countries have initially motivated the Member States of the North American Free Trade Agreement, then other states and the European Union, to adapt their international investment agreements to try to implement the concept of fair and equitable treatment and to limit the assessment of arbitrators. The concept of fair and equitable treatment has also received a great deal of attention from scientists who propose a multitude of different approaches to interpreting the standard and balancing competing private and public interests.
With the guarantee against the illegal expropriation of an investment, the most frequently invoked standard is asset protection.