Leading Article: A drug that could save a lot of pain

SCIENTISTS believe that it is less addictive than morphine, and has fewer hallucinogenic effects than drugs such as LSD. Yet cannabis is banned from the pharmacies, hospitals and GPs' surgeries where other 'harder' drugs are allowed. Except in closely controlled research programmes, it cannot be used by doctors to treat their patients - despite the anecdotal evidence suggesting that cannabis is a useful muscle relaxant and a painkiller with few side-effects.

By raising the possibility that cannabis might be made legal on prescription, Baroness Cumberlege has brought British pharmacological policy at least a step towards reality. When a substance presents itself that may do good to people who are ill or in chronic pain, and may do so more safely and cheaply than drugs already on the market, there can be no sense in outlawing it for purely emotional reasons.

But those who suffer from multiple sclerosis, cancer and other ailments for which cannabis is being used informally (and illegally) as treatment would be unwise to hold their breath. It will undoubtedly be years, rather than months, before an extract of cannabis becomes available on chemists' shelves alongside the synthetic cannabinoid launched last summer by Lilly Industries.

The licensing of cannabis on prescription may also have a wider effect on British drug policy. The Independent, along with some judges and senior police officers, has long argued for a limited legalisation of drugs. The argument for change is that outlawing these drugs has done little to prevent their use, but has brought huge profits to the gangsters who deal in them - and has contributed to the collapse of civil society by forcing addicts to beg, burgle, mug or kill in order to pay for their habit.

There is, however, an entirely separate argument about the legalisation of cannabis. Its enthusiasts concede that cannabis, like alcohol, has unmistakable bad effects if used to excess (though it is less likely to make people aggressive). But they insist that the occasional joint does no more harm than the occasional cigarette, and probably a great deal less.

There has never been enough hard scientific evidence to assess the value of this argument. But if cannabis were to become legal on prescription, that might change. With evidence from thousands of patients over years of use, the argument could be settled once and for all. Gathering such knowledge would vindicate the policy of looking at this drug in a dispassionate, less emotional light than has hitherto been the case.