Dame Ruth Runciman, the UKDPC chairwoman, said while Government programmes to reduce the damage caused by drug problems - like needle exchanges and investment in treatment for addicts - are supported by evidence, "much of the rest of drug policy does not have an adequate evidence base."
We spend billions of pounds every year without being sure of what difference much of it makes.
A fellow commission member, the former chief executive of the Medical Research Council Professor Colin Blakemore, added:
Medicine has moved past the age when we treated disease on the basis of hunches and received wisdom. The overwhelming consensus now is that it is unethical, inefficient and dangerous to use untested and unvalidated methods of treatment and prevention. It is time that policy on illicit drug use starts taking evidence seriously as well.