1.1 In October 2001
the Home Secretary asked the Advisory Council on the
Misuse of Drugs (the Council) to review
the classification of cannabis preparations in the
light of current scientific evidence.
1.2 The Council is
established under the Misuse of Drugs Act 1971 to
keep under review the drug situation in the United
Kingdom and to advise government ministers on the
measures to be taken for preventing the misuse of
drugs or for dealing with the social problems
connected with their misuse. In particular, the
Council is required to advise on the appropriate
classification of substances being specified under
Part I, Part II, and Part III of Schedule 2 to the
classification of drugs, in Schedule 2 to the Misuse
of Drugs Act 1971, is based on the harm they may
Class A (the most
harmful) includes morphine and diamorphine (heroin).
Class B (an
intermediate category) includes amphetamines,
barbiturates, cannabis and cannabis resin.
Class C (the least
harmful) includes anabolic steroids, benzodiazepines
and growth hormones.
1.4 When advising on
the harmfulness of drugs, the Council takes account
of the physical harm that they may cause, their
pleasurable effects, associated withdrawal reactions
after chronic use, and the harm that misuse may bring
to families and society at large.
1.5 The Misuse of
Drugs Regulations 2001 (Statutory Instrument
2001/3998) defines the categories of people
authorised to supply and possess drugs controlled
under the Act. In these Regulations, drugs are
categorised under five schedules:
includes drugs such as cannabis that are not,
conventionally, used for medical purposes.
Possession and supply are prohibited without
specific Home Office approval.
includes morphine and diamorphine and are subject
to special requirements relating to their
prescription, safe custody and the need to
includes barbiturates and are subject to special
prescription, though not safe custody
includes benzodiazepines and are neither subject
to special prescription or safe custody
includes preparations that, because of their
strength, are exempt from most of the controlled
2.3 This Report
considers the most appropriate Class (see paragraph
1.3) into which cannabis preparations should be
categorised based on its harmfulness.
2.4 The Report
itself is based on a detailed scrutiny of the
relevant scientific literature including four reviews
commissioned by the Department of Health in 1998 as
well as an update commissioned by the Home Office and
completed in November 2001.
4. Risks to human
4.1 Drugs affect
health in a number of different ways. They can
produce immediate adverse medical effects (such as
death from respiratory depression with heroin) or can
damage health over a period of time (such as lung and
heart disease from smoking tobacco).
sedative intoxicants such as alcohol, cannabis does
not cause respiratory depression or suppress the gag
reflex even when extremely intoxicated.
differs from alcohol, however, in one major respect:
it seems not to increase risk-taking behaviour. This
may explain why it appears to play a smaller role
than alcohol in road traffic accidents. Cannabis
intoxication tends to produce relaxation and social
withdrawal rather than the aggressive and
disinhibited behaviour commonly found under the
influence of alcohol. This means that cannabis rarely
contributes to violence either to others or to
oneself, whereas alcohol use is a major factor in
deliberate self-harm, domestic accidents and
smoking is the largest single cause of ill health and
premature death in the UK. In general cannabis users
smoke fewer cigarettes per day than tobacco smokers
and most give up in their 30s, so limiting the
long-term exposure that we now know is the critical
factor in cigarette-induced lung cancer.
studies of lung function in regular cannabis smokers
have not found a major cause for concern in the
4.4.5 It is possible
to rank the risks of dependence of abused drugs with
heroin and crack cocaine the worst and cannabis
generally at, or near, the bottom (and well below
nicotine and alcohol).
4.4.6 The other main
concern about the chronic use of cannabis is whether
it can lead to mental illness (especially
schizophrenia). Although debated for well over a
century, no clear causal link has been demonstrated.
4.4.8 There is no
evidence that cannabis causes structural brain damage
smoking and alcohol use are significant causes of
harm to the unborn child. Cannabis may also increase
the risk of minor birth defects and abortion but the
effect is small.
4.5.2 There is some
evidence that smoking cannabis during pregnancy may
produce subtle alterations in neuropsychological
performance of the child that persists into later
life. This effect is similar to that of tobacco
smoking and may be due to the actions of tobacco
smoke rather than to cannabis per se.
4.5.3 Taken together
this data suggest that cannabis use in pregnancy is
not safe but that it is probably no more dangerous to
the foetus than either alcohol or tobacco.
4.6.2 the use of
other substances such as alcohol, tobacco, solvents,
stimulants and psychedelic agents ... generally also
precedes that of Class A drugs.
4.6.3 other studies
have found that the use of alcohol and tobacco in
early teens (and especially in pre-adolescents)
appears to be associated with the later use of many
drugs including cannabis.
4.6.4 it is likely
that cannabis use (and that of alcohol or tobacco)
has an effect on later Class A drug use.
appears not to make as major a contribution to road
traffic or other accidents as alcohol.
5.1 The apparent and
ready availability of cannabis is, however,
disproportionate to the relatively small numbers of
people seeking help from drug treatment agencies for
cannabis misuse. The high use of cannabis is not
associated with major health problems for the
individual or society.
5.2 The occasional
use of cannabis is only rarely associated with
significant problems in otherwise healthy
individuals. These harmful effects of cannabis,
however, are very substantially less than those
associated with similar use of other drugs, such as
amphetamines, which (like cannabis) are currently
classified as Class B.
5.4 Regular heavy
use of cannabis can result in dependence, but its
dependence potential is substantially less than that
of other Class B drugs such as amphetamines or,
indeed, that of tobacco or alcohol.
5.5 It is not
possible to state, with certainty, whether or not
cannabis use predisposes to dependence on Class A
drugs such as heroin or crack cocaine. Nevertheless
the risks (if any) are small and less than those
associated with the use of tobacco or alcohol.
6.1 Cannabis is not
a harmless substance and its use unquestionably poses
risks both to individual health and to society.
however, is less harmful than other substances
(amphetamines, barbiturates, codeine-like compounds)
within Class B of Schedule 2 to the Misuse of Drugs
Act 1971. The continuing juxtaposition of cannabis
with these more harmful Class B drugs erroneously
(and dangerously) suggests that their harmful effects
are equivalent. This may lead to the belief, amongst
cannabis users, that if they have had no harmful
effects from cannabis then other Class B substances
will be equally safe.
6.3 The Council
therefore recommends the reclassification of all
cannabis preparations to Class C under the Misuse of
Drugs Act 1971.
Levels of use
a commonly expressed
concern has been that a downward reclassification
would lead to an increase in use. In attempting to
analyse the likely impact on prevalence of
reclassification, there is very little relevant
domestic learning to draw on. But it is possible to
look at the experience of other countries, albeit in
circumstances where civil penalties have replaced
criminal sanctions. In particular, the experiences in
Australia, the Netherlands and the United States are
illustrative. In each of these countries a reduction
in the penalties for using cannabis has not led to a
significant increase in use.
In announcing any
change to the classification of cannabis, it will be
important to ensure that the decision and the reasons
for it are properly understood. We have tried to
express as clearly as we can in this Report the
message that cannabis is a harmful drug. But much of
the debate about cannabis and about the appropriate
response of society to its use tends to overlook this
More generally, the
provision of accurate and objective advice on the
health effects of all drugs, and where to access
treatment, must be a key part of our drug strategy.
In respect of cannabis, the Council hopes that this
Report represents a modest contribution to that