ABSTRACT
This chapter examines the scope ratione materiae of the international drug control system, analysing which substances this system applies to. It provides the actual and potential scope of application of the international drug control system. Conversely, some conceive that the scope of application of the international drug control system should be enlarged and extended to include even more substances hitherto left outside its scope of control. According to this narrative, the international drug control system would be too inflexible in order to swiftly react to changing patterns of recreational drug use and drug abuse. This material inflexibility of the Single Convention is at odds with the very idea of providing for a flexible legal framework by introducing schedules. The chapter concludes by examining whether the international drug control system is of adequate flexibility to react swiftly to the appearance of 'new psychoactive substances' which have hitherto remained outside its scope of control.
