investigative file but relates to the accused’s ability to meet the
case for the Crown, to raise a defence or to make decisions about
the conduct of the case for the defence. For disclosure purposes,
relevance is not determined by whether the information sought is
decisive in the case, rather by its logical relevance. This is not
a stringent standard.
 A rolling log reflects the DRE’s experience with the 12-step
evaluation test to determine drug impairment. It shows how
many times the DRE has conducted the test. The drug groups
identified. The toxicological results, whether confirmatory or
contradictory of the DRE’s opinion.
 Second, prior experience and present reliability.
 In the law of evidence, we recognize that how an individual acted on prior occasions is relevant in deciding whether or
how they acted at a material time. Although admissibility rules
rooted in policy considerations may exclude this evidence in some
circumstances, as for example when tendered by the Crown,
exclusion is not based on lack of relevance. In a similar way, we
test the reliability of current information from a confidential
informer by examination of the track record (or the absence of
a track record) of that informer.
 Third, the impact of the DRE’s evidence.
 As we have seen, the DRE’s opinion on drug impairment,
formed by inference from the results of the 12-step evaluation, is
not dispositive on the issue of drug impairment. For the DRE cannot describe the effect of any drugs found through toxicological
analysis on the mental or physical ability of an accused to operate
a motor vehicle. The DRE’s opinion on drug impairment is a link
in the Crown’s chain of proof. Like other links in that chain, it is
open to challenge.
 The appellant’s analogy to Jackson and Gubbins is misplaced. There, the appellants sought disclosure of historical records about the performance of the approved instrument on other
occasions. The material issue in each case was not of course how
the approved instrument had performed on those prior occasions,
but how it actually worked when the appellants’ breath was tested.
Expert evidence confirmed that historical data could tell nothing
of that. And there were also several pre-test steps, mechanisms to
ensure that the instrument would only function if operating
properly. But that is not this case. No expertise is required to
establish the relevance of prior experience to current reliability.
 Fourth, the curriculum vitae.
 A threshold requirement for the admissibility of expert
opinion evidence is a properly qualified expert. It is commonplace
for those proposed as experts to record their qualifications in