1.  I have appeared in court as an expert witness in numerous cases where defendants have claimed to be using cannabis for therapeutic purposes, either in mitigation or claiming necessity. Most Crown Court trials, where defendants have invoked the defence of "duress of circumstances", have resulted in jury acquittals on all charges.

  2.  Irrespective of policies on other aspects of drug legislation, this issue should be addressed as a matter of urgency. The Attorney General should draw up guidelines for prosecuting authorities as many prosecutions clearly fail to take account of either the reasonable prospects of a conviction, or whether such a prosecution would be in the public interest.

  3.  At present, prosecutions would fail to reach the 51 per cent threshold in all cases involving simple possession or personal cultivation (production) for relevant medical conditions (including chronic pain, multiple sclerosis and other movement disorders, cancer chemotherapy or AIDS, epilepsy or glaucoma. Perhaps a designated list should be maintained of conditions for which prosecutions should not proceed where a medical diagnosis is provided. In cases of supply to a medicinal user, prosecutions are again unlikely to succeed, nor would "possession with intent" charges on relatively large amounts claimed to be for personal use, unless there is other (paraphernalia) evidence of dealing. In cases of other medical conditions, the CPS should seek expert advice before contemplating prosecution.

  4.  Such a policy should not fetter the hands of the CPS where medicinal use is incidental to commercial supply of drugs, or other criminal offences.