Pubdate: Sat, 20 Apr 2002
Source: New Scientist (UK)
Copyright: New Scientist, RBI Limited 2002
Author: Bruce Symington, Alberta, Canada
Bookmark: (Cannabis)


You report on an investigation of the relative effects of drinking 
and cannabis consumption on driving ability (23 March, p 4). While 
the article is right that there is no known test specific for 
impairment caused by cannabis, it didn't mention other tests which 
have been developed to assess the overall ability to drive, one of 
which measures the subject's ability to find and focus on 
intermittent lights. This test and others look for impairment from 
whatever source.

The opponents of substance testing rightly point out that the effects 
of different substances vary between individuals, and in the same 
individual over time and in different circumstances. When the 
authorities begin testing for impairment rather than the presence of 
substances in the body they will be on the right track.
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MAP posted-by: Josh