Discussing the standards of legal treatment for international investment, means subjecting the law branch in its entirety to research. Representing the most comprehensive part, of particular importance for international investment law, treatment standards continue to generate a series of differentiations whose understanding and approach often require the analysis of the starting points that led to the emergence, by division, of this branch of law. International investment treatment standards represent or should represent the direct effect of the principles of international investment law, thus being their expression, with a pronounced logical affinity between them. Specifically, they are not confused with the principles, but they are the practical reflection at the level of rights and obligations, applicable to the performers in this field, in the highlight of the theoretical-practical aspect, having a customary origin, as well as the principles underlying their development. Following this logic and analyzing the situation of the latest investment treaties, it turns out that there is an insufficiency in the preponderance of treatment standards, compared to the principles, much more numerous and constantly expanding, of this field of law. The specificity of this branch of law consists in the emphasis on its fundamental concepts, essentializing what determines the whole, being considered as a science of essentialization and, ultimately, the role of any method of scientific research is to analyze, discover and highlight what this branch of law represents, as a whole, what determines it, the connections of this ensemble with other sciences, the composition and structuring of the system and the substantiation of the connections between its components. The standards of legal treatment of international investments settled with the individualization of international investment law. Their appearance took place gradually, depending on the path marked by the stages of emergence and evolution of the legal regime of foreign investment, from the legal phenomenon to the branch of law, from trade in general to foreign investment in particular. In all of this, legal scientific research plays a key role because any codification activity must be scientifically substantiated. Any codification policy must ensure a balance between the diachrony and the synchrony of international investment law (between the dynamics and the statics of this law). A complete analysis of the treatment standards of international investments can be performed only by a close correlation because the singular existence of a standard specific to this field is excluded from the start. The importance of establishing and existence of eloquent and integrated treatment standards is a condition for survival under international economic crises. The main feature of this monograph is to present the subject in a way that is as easy to understand as possible to study and apply such rules, being a very useful and valuable material for students, masters, doctoral students, theoreticians and practitioners.