This chapter focuses on legal concepts and legal issues that do not represent the central point of focus of the book, but which form an important part of the overall topic. Each of the issues addressed in this chapter significantly impacts the legal framework applicable to a particular case. This concerns circumstances of applicability of the selected fields of international law and jurisdiction of investment tribunals to take into account specific fields of international law other than international investment law. Also, the issue of termination and suspension of treaties is briefly addressed, given the fact that the existence of armed conflict may have such an effect on bilateral investment treaties, on various grounds. Finally, also derogation from human rights obligations is briefly mentioned. With respect to each of these specific areas, the chapter briefly explains the legal framework and issues associated with it and adopts presumptions for the following substantive chapters.