My Lords, like the noble Lord, Lord Walton, who spoke last week during the supplementaries on the Question for Oral Answer
tabled by the noble Baroness, Lady Meacher, on this topic, I served on the Select Committee which looked into the medicinal use of cannabis. One of the central recommendations was exactly what the noble Lord, Lord Ribeiro, has suggested. We need controlled trials. The noble Baroness has just backed up that suggestion as well. But it is very difficult to get these trials going. As she has said, because cannabis is an illegal substance, it is difficult to get people to agree to do the work. One or two trials have been carried out which resulted in the production of Sativex, but only one firm is producing it. As the noble Baroness said, it is terribly expensive and can be prescribed only on a named basis; it is very difficult for doctors to prescribe it to patients who have been shown to benefit from cannabis by getting it illegally.
One of the problems with getting cannabis illegally is that you do not know the ratio of the different cannabinoids in the illegal drug. It has been shown—this was told to us in our committee—that there is a huge range of effects from different cannabinoids. The one that gives the psychoactive effect, tetrahydrocannabinol— THC—is something that people who take cannabis for medicinal purposes do not like. But it is very difficult to find an illegal version of cannabis that contains a good ratio with more cannabidiol—CBD—which is the calming one that reduces spasms. Sometimes people have thought that it does not stimulate psychotic results but prevents them; it is an antipsychotic drug.
So there are real reasons why it should be made legal for researchers to concentrate on doing proper, controlled clinical trials to work out what cannabis can do, and what components or mixtures of cannabis components are most effective. This is crying out to be done, but as things are, it is very difficult to get scientists to agree to do it because of the illegality of the substance.