Demonstrate a failure to follow required steps. Or reveal the
questionable nature of the DRE’s inferences. Evidence of bodily
sample analysis or testimony from lay witnesses or experts may
rebut or discredit the DRE’s assessment: Bingley, at para. 32.
 And in the end, as with any item of evidence adduced in
a criminal trial, it will be open for an accused to challenge and for
the trier of fact to assess the weight to be assigned to the DRE’s
opinion about impairment: Bingley, at para. 32.
Section 657.3 of the Criminal Code
 Section 657.3 of the Criminal Code enacts notice and disclosure requirements when expert opinion evidence will be tendered
for admission in a criminal trial. Among other things, s. 657.3(3)(a)
requires a party to provide disclosure of a “statement of the
qualifications of the proposed witness as an expert” to the other
party or parties.
The principles applied
 As I will explain, I would not accede to this ground of
appeal. I agree with the conclusion of the trial and motion judges
that disclosure of the rolling log is governed by the first party disclosure regime of Stinchcombe, not the third party scheme of
O’Connor. However, as will become apparent, I reach my
conclusion for reasons that differ from those of the trial and
 The touchstone of disclosure is relevance. No one has
a right to disclosure of information or material which lacks logical
relevance. And no one has a duty to disclose information or
material which lacks logical relevance.
 In this case, the Crown must prove beyond a reasonable
doubt that, at the time alleged, the respondent’s ability to operate
a motor vehicle was impaired by a drug or a combination of
a drug and alcohol. As part of its proof, the Crown may tender as
evidence the opinion of the DRE who conducted the drug
recognition evaluation of the respondent.
 In the absence of any statutory provisions displacing
them, the common law rules governing the exceptional admission
of expert opinion evidence apply in prosecutions for drug-impaired operation. In the result, the admissibility of expert
opinion evidence requires a two-stage analysis.
 The first stage considers whether the proposed evidence
satisfies the four Mohan factors including that the proposed
witness have special expertise beyond the knowledge and
experience of the trier of fact. Evidence that fails to meet the
Mohan threshold requirements will be excluded.