Hi MizzCarmen,
Its rather a broad question. Most of what you would refer to as synthetic drugs are regulated under the Drugs, Poisons and Controlled Substances Act in VIC. This act prescribes the offences relating to manufacture, possession and supply of all sorts of drugs and provides information as to the specific schedule of poison they are classified as. The act not only applies to illicit drugs but obviously also therapeutic drugs - which can also be distributed or used "illegally".