DETECTING MARIJUANA IMPAIRMENT

Q: I recently overheard a conversation between young people where
they discussed the daily use of marijuana - on their way to and from
school and in their cars. They said it did not affect their ability
to drive and that it went undetected by parents, teachers, employers
and the police.

Could you please discuss what methods are available, if they are
being utilized to identify drivers under the influence of marijuana
and how effective they are?.

A: I did not receive Drug Recognition Expert (DRE) training during my
traffic enforcement service, but I was able to work alongside others
who had been trained, and learned enough to be confident of my
decisions when I issued 24-hour prohibitions for the use of marijuana.

A driver under the influence of marijuana is more difficult to detect
than most other illegal drugs, but the drug does produce the
following symptoms: bloodshot eyes, accelerated heart rate
(tachycardia), muscle tremors and forgetfulness. Marijuana
impairments include: difficulties with judgment, depth perception and
the ability to maintain attention. All of these skills are necessary
for the safe operation of a motor vehicle.

How effective are drug recognition experts? A driver may be convicted
of driving while impaired by a drug based on driving or care and
control evidence and the impairment evidence given at trial by the
DRE. Recent amendments to the Criminal Code have significantly
expanded the use of the DRE by making it a requirement for a
suspected impaired driver to submit to an exam rather than
voluntarily participate.