Pubdate: Wed, 09 Aug 2000
Source: Evening News (UK)
Copyright: Eastern Counties Newspapers Group Ltd,2000
Author: Don Barnard


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

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

Have the police been ordered to pursue and identify more and more

Whatever, we are surely in for a testing time.

Don Barnard
Aetheric Road
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