In New Zealand, the presumption of supply is a rebuttable presumption in criminal law which is governed by the New Zealand Misuse of Drugs Act 1975. It provides an assumption in drug-possession cases that if a person is found with more than a specified amount of a controlled drug, they are in possession of it for the purpose of supply or sale. This shifts the burden of proof from the Crown to the person found with the drug, who must prove that they possessed it for personal use and not for supply. Note that once the burden of proof has shifted, the burden is one on the balance of probabilities (rather than beyond reasonable doubt). This presumption exists to make prosecution for supplying drugs easier. In 2007, the Supreme Court ruled that the presumption of supply is inconsistent with section 25(c) of the New Zealand Bill of Rights Act 1990. History Although drug regulation began in New Zealand with the regulation of opium during the late 19th century, it was not until 1965 that the offence of supply was differentiated from that of possession. Single Convention on Narcotic Drugs 1961 During the 1960s, the United Nations consolidated and broadened earlier drug treaties. The Single Convention on Narcotic Drugs 1961 came into force in 1964 when 40 countries, including New Zealand, ratified it. The convention, influenced by the United States prohibition model of drug regulation, was ratified by New Zealand in 1963. In its commentary on the convention, the United Nations General Assembly endorsed the use of presumptions. Narcotics Act 1965 New Zealand implemented the 1961 convention in its Narcotics Act 1965. The Narcotics Act introduced a distinction between offenders who trafficked in narcotics and those who possessed (or used) them, with penalties for drug dealing much harsher than those for possession or use. In support of this, the act introduced a presumption of possession for the purpose of supply. When a person was found in possession of an amount of a scheduled drug exceeding a specified level, the burden of proof shifted to the accused to prove that the drugs were for personal use and not for supply to others. If the person could not meet this burden, they could be convicted of the more serious offence of dealing narcotics. Misuse of Drugs Act 1975 The Misuse of Drugs Act 1975 continued the policy introduced in the Narcotics Act by