This chapter explains the basis of the access to justice obligations placed on international organisations (IOs) under international law. One foundational issue is whether or not IOs are capable of being placed under international obligations in general. The answer to this question, as this chapter will show, is most certainly in the affirmative. IOs are international legal persons or ‘subjects’ of international law that possess their own legal personality. This means that international law can bind IOs directly and impose obligations that ought to be implemented by the IO. After showing how international law can directly place IOs under international obligations in general, the focus shifts to whether IOs can be placed under access to justice obligations in particular. The chapter discusses what is meant by access to justice as a value, and how that value has translated into legal rights in the form of the right to a fair trial. The discussion then clarifies how IOs specifically are put under access to justice obligations, including demonstrating the rationale behind doing so. It is argued that IOs are required to provide justice consistently with fair trial guarantees to private persons whenever IO actions adversely impact them.