My experience is that disclosure has become shakier and shakier during the pandemic. Police and Crowns offices are not doing well in terms of putting disclosure together.
The key to any successful DUI defence these days seems to be either a good Charter issue (usually right to counsel or unreasonable delay) and low readings.
However, defence lawyers need to take a closer look at the conditions precedent to the presumption of accuracy under section 320.31(1). The Crown has an obligation to prove the 320.31(1) conditions precedent beyond a reasonable doubt. Recent case law shows that they can do that, at least prima facie, through service and filing of a Certificate of a Qualified Technician and/or the Intoxilyzer Test Record or alternatively through hearsay evidence from the Qualified Technician. If the defence simply cross-examines the QT on the documents in an attempt to raise a reasonable doubt, the prima facie proof is probably enough for the Crown, and probably won't be enough for the defence to raise a reasonable doubt. We need to do better than that.
The defence needs to raise "evidence to the contrary". I'm not suggesting "evidence to the contrary" to rebut conclusive proof of BAC- you can't do that. I'm talking about Interpretation Act 25(1) "evidence to the contrary" directly related to:
"the qualified technician conducted a system blank test the result of which is not more than 10 mg of alcohol in 100 mL of blood and a system calibration check the result of which is within 10% of the target value of an alcohol standard that is certified by an analyst"
or
"there was an interval of at least 15 minutes between the times when the samples were taken"
or
"the results of the analyses, rounded down to the nearest multiple of 10 mg, did not differ by more than 20 mg of alcohol in 100 mL of blood"
This different kind of "evidence to the contrary" will not relate to the accuracy of the subject tests. The "evidence to the contrary" will not relate to reliability of the subject tests. The "evidence to the contrary" will not involve the use of an expert toxicologist talking about absorption, distribution, and elimination of alcohol in the human body. (That is, unless that toxicologist also happens to be an expert in good laboratory practice.) You will need instead, an expert on how evidentiary breath measurement systems check ambient conditions, conduct control tests, and conduct a fuel cell or IR indication using breath to produce a BAC analysis. That expert will probably have expertise well beyond evidentiary breath instruments and extend into physics and/or good laboratory practice in metrology. Their evidence will focus on the 320.31(1)(a) air blanks or the control tests, the 320.31(1)(b) clock, and/or the 320.31(1)(c) good agreement and reporting systems.
An unreliable control test or an unreliable air blank can still produce an accurate BAC result, accidentally, but the control test or air blank are still unreliable, and shouldn't comply with 320.31(1)(a). The Crown shouldn't be able in such circumstances to make use of section 320.31(1) conclusive proof, but the Crown will be successful, if the defence can't produce Interpretation Act 25(1) "evidence to the contrary" to rebut the presumptions in section 320.32(1) (Certificate of QT and Certificate of Analyst), 320.33 (Intoxilyzer Test Record), or the hearsay by the Qualified Technician.
An unreliable control test or an unreliable air blank with an allegedly accurate subject test result may still result in proof at common law, but that is another issue requiring a different kind of trial with different relevant evidence and perhaps old fashioned Carter or St-Onge "evidence to the contrary".
Interpretation Act section 25(1) reads:
25(1) Where an enactment provides that a document is evidence of a fact without anything in the context to indicate that the document is conclusive evidence, then, in any judicial proceedings, the document is admissible in evidence and the fact is deemed to be established in the absence of any evidence to the contrary.
The Interpretation Act statute says that the fact is deemed to be established. Once filed, the facts stated in the Certificate of Qualified Technician or Intoxilyzer Test Record are deemed established. Case law indicates that hearsay evidence from the Qualified Technician has the same status.
Defence counsel should ensure that they have evidence ready that contradicts the Certificate of the QT, the Intoxilyzer Test Record, and the Crown's hearsay evidence. That evidence will probably include a defence expert. That evidence will require good cross-examination.