The Controlled Substances Act 1984 (SA) and related regulations are quite complex but in broad terms distinguish between drug users, who face lesser penalties, and producers or suppliers who generally face greater penalties [see Brief Penalty Summary - Controlled Substances Act (below)]. In addition, the Act distinguishes between controlled drugs, drugs of dependence, prescription drugs, controlled plants (including cannabis) and controlled precursors. There are other categories which are not relevant for the purposes of this chapter. It is important to note upfront that in some very important aspects cannabis is dealt with differently from other substances.

The principal Act was substantially and significantly amended by the Controlled Substances (Serious Drug Offences) Amendment Act 2005 (SA). Some of the amendments came into operation on 12 January 2006, with the remainder commencing on 3 December 2007. The provisions as amended only apply to offences committed on or after the date the particular provision came into effect [see Controlled Substances (Serious Drug Offences) Amendment Act 2005 (SA) sch 1 pt 6]. Since 2005, other Acts have introduced further amendments [see Controlled Substances Act 1984 (SA) - Legislative history for relevant Acts].