Ever since the first international drug control agreements in the early 20th century, the focus of policy has been on tackling the supply of illegal drugs - by preventing their production and distribution, and arresting and prosecuting users. This strategy was based on the belief that the successful reduction of the availability of potentially harmful substances was the simplest and most reliable way to reduce the harmful consequences of their use. After 100 years of drug control, there are basically two reasons why this paradigm has become outdated:

• The ability of governments and international agencies to stifle the global market in drugs such as Cannabis, Heroin and Cocaine has been limited. Despite localised successes, and the increased concentration of Opium production in Afghanistan, and Cocaine production in Colombia, the scale of the global trade in these substances increased massively in the second half of the twentieth century, and has remained stable at best over the last 10 years. At the same time, the supply mechanisms for drugs such as Cannabis and Amphetamine-type Stimulants (ATS) have become significantly more diverse - with a vast number of small scale production and dealing operations, and increasing levels of home production - making them less vulnerable to national or international enforcement efforts. On the few occasions when supply of a particular drug from a particular source has been stopped, suppliers quickly move to another source, or users move to another drug. Measured in terms of price, purity or ease of availability, illegal drugs are now more accessible in most parts of the world than they were 10 years ago, when we set out on the latest global strategy, that promised significant progress in "...eliminating or reducing significantly the illicit cultivation of the coca bush, the cannabis plant and the opium poppy...". This state of affairs cannot be claimed as a policy success.
• Governments and local administrations have increasingly implemented policies and programmes that are not directly aimed at reducing the scale of the drug market, but that target specific consequential harms arising from drug use - for example, public health measures to prevent overdose deaths and HIV infection, or local action to tackle petty crime associated with drug markets. The key objectives of these policies and programmes are the reduction of the consequential harms, rather than the reduction of drug use itself. Many governments now explicitly recognise in their national and local strategies that a certain level of drug use in their societies is inevitable, and that their prime responsibility is to minimise the harmful consequences. This position has been strengthened by an expanding evidence base demonstrating that properly designed and implemented public education, health promotion, and crime reduction programmes can be effective in mitigating the most negative consequences of drug use. The increasing support for these programmes has led to a growing disconnect between the domestic policies pursued by many governments, and the continued emphasis on supply reduction policies and investment that is promoted through international mechanisms.

The tensions that arise between a simple focus on fighting supply, and the more complex set of policies focussed on reducing harmful consequences, need to be resolved within national strategies and international programmes. Many national governments now comfortably incorporate objectives relating to drug supply, drug demand, and also harmful consequences. In 1998, the United Nations incorporated objectives relating to demand reduction into its policy and programmes, in order to complement the previous supply reduction focus. The next challenge for the international community will be to find a way of incorporating objectives and programmes relating to the reduction of harmful consequences into international agreements.