Dangerous Drugs Act 1920: criminalising opium and cocaine possession

Before the First World War, Britain had signed the International Opium Convention at The Hague in 1912. This imposed stricter controls on doctors and pharmacists in relation to dangerous drugs and committed countries to preventing trade in morphine, opium and cocaine.

Later, in 1916, the army council enacted Defence of the Realm Act regulation (emergency legislation-making powers during wartime), to prohibit the sale of cocaine and opium to troops. The legislation was widened to criminalise civilian possession of those drugs without a medical need.

The 1920 Dangerous Drugs Act incorporated the provisions made under the Defence of the Realm Act regulations. The Act established that medical practitioners were allowed to prescribe morphine, cocaine and heroin.

The Act set the agenda for further drug legislation and control policy and reinforced the Home Office's precedence over the Ministry of Health. The regulations came into force on 1 September 1921.

Later, the 1928 Dangerous Drugs Act imposed restrictions on cannabis.