Proportionality is one of the key principles of the rule of law aiming to protect people from cruel or inhumane treatment. The principle has been established in international and regional human rights agreements and many countries have adopted reflections of it in their constitution or penal code. Its application to drug-related offences is firstly the responsibility of the legislators, in defining the level of penalisation of certain behaviours.
Distinguishing between drug possession for personal use and supply and trafficking is widely acknowledged as one of the most difficult and controversial issues facing drug legislators and policy makers.