DRUG TESTS ARE A WORRY

YOUR report on Friday, August 4, about police testing drivers for drug use
at first glance seems like a good idea.

However, aside from the fact that there is no real evidence to show that
cannabis-users are more susceptible to accidents than non-users, it is also
questionable whether a positive drug-screening test is precise enough to
supply the formal proof needed for prosecutions, such as driving under the
influence of cannabis.

Due to the varying rates at which drug metabolites can appear in an
individual's blood, proving impairment through taking any drug is far from
clear-cut.

Cannabis metabolites can be detected in the urine for up to 90 days after
use. Any standard levels of presumptive impairment for cannabis become
meaningless in practical application.

There are also several causes of inaccurate readings, including problems of
interfering substances.

Codeine tests positive for metabolised opiates for up to four days after
use. Poppy seeds found on seeded bread test for opiates for up to 60
hours. Cannabis seed oil is recognised as causing false positive test
results for cannabis.

Further, drug tests provide no evidence or information as to their effects
on an individual's ability or performance. They cannot establish the date
or time of use and an individual can test positive for illegal substance use
without consuming them.

This raises both social and legal issues, if drug tests cannot prove or
disprove the offence of using drugs or of impairment through drug use.

Is this a road safety measure or a new strategy in the war on drugs?

Don Barnard, Aetheric Road, Braintree