1. The law currently prohibits driving "whilst
unfit through drink or drugs". The current law does not require
major modifications to be effective. However, there may be a case
for secondary legislation to be amended to provide more effective
2. To secure a conviction, the police/Crown
must prove that:
(a) The driver was under the influence of
(b) His ability to drive properly was for
the time being impaired,
(c) That the impairment was due to drugs
rather than other factors (eg disability, illness, fatigue etc).
3. IDMU has been consulted by the Transport
Research Laboratory and Northamptonshire Police in developing
more effective methods of enforcement for the existing laws.
4. The "field impairment testing"
(FIT) currently being adopted by many police forces, represents
an improvement on previous enforcement techniques, but fails to
address abilities which are directly related to the ability to
drive, in particular reaction time and tracking ability. These
could be addressed via development of an in-car simulator to allow
suspects to be tested at the time, with objective pass/fail standards.
We have also recommended that all FIT tests are recorded on videotape
where such facilities exist within a police vehicle, as too much
of the present test is subjective on the part of the police officer
5. The taking of samples of blood for drugs
provides a snapshot at the time the sample is taken, which may
represent a baseline level or the residue of a higher dose influencing
the driver at the time (particularly for cases involving cannabis).
We recommend that legislation be amended to require the taking
of at least two samples a fixed time (eg 15 minutes) apart to
determine whether a drug level is stable or declining, and to
enable back-calculation to the time of the incident in question.
6. Despite much public alarm, the effect
of most controlled drugs on driving provides less of a risk of
accidents than alcohol or prescribed benzodiazepine drugs:
(a) CannabisIncreased risk for new
users or new drivers, for established users/drivers appears to
reduce accident risk by improving driver behaviour (slower speeds,
larger gap, fewer risky manoeuvres) compensating for any performance
impairment (tracking ability may be affected, no effect on reaction
(b) StimulantsLow doses of amphetamine
or cocaine may improve performance (alertness, quicker reaction
times), although high doses impair judgement (overconfidence,
(c) OpiatesImpair naive users, addicts
probably drive better with drug in system than when withdrawing,
(d) EcstasyOur surveys suggest significantly
increased risk of accidents, but may be confounded by social factors
(eg fatigue due to driving in the small hours of the morning when
returning from clubs/raves),
(e) Hallucinogenssevere impairment
of perception and judgementfew users would contemplate
driving under the influence.