Welcome to British Columbia’s only weekly DUI law update newsletter. This newsletter contains the most cutting-edge information, the newest case law, and helpful practice tips for DUI defence in BC.
Authored by Kyla Lee, BC’s Impaired Driving Update is released weekly on Thursdays.
What’s Inside:
- Immediate Roadside Prohibition Review Tips
- IRP Review Decision updates and successes
- DUI Decision of the Week: a helpful DUI case precedent
- Kyla’s Insight
1. Immediate Roadside Prohibition Review Tip of the Week
Pay close attention to officer narratives. Oftentimes, with a keen eye, you can spot officers using templates. This can include spotting instances in which an officer may mistakenly refer to the person by the wrong gender or somebody else’s name creeps into the narrative. This can then be used to call into question the credibility of the police evidence, particularly if the error matches something where there is a dispute in the evidence between your client and the officer.
2. IRP Decision of the Week
Prohibition Revoked: An officer pulled a driver over leaving the parking lot of a bar. A mandatory demand was read. After reading the demand, the officer asked the driver when he had his last drink. The driver responded it was 15 minutes earlier. The officer conducted two ASD tests, both of which were completed within three minutes of the time of driving. No waiting period was held to accommodate the driver’s margin of error in his estimate.
Kyla Lee argued that the ASD test results were more likely to be unreliable as the driver could not reasonably have been speaking with certainty when saying fifteen minutes. The probability was the alcohol was consumed less than 15 minutes before both tests. Given how short of a time passed between when the first test was administered and when the second test was administered, both tests could have been impacted by mouth alcohol.
3. DUI Decisions of the Week
R. v. Rouselle, 2025 SCC 35; R. v. Laroque, 2025 SCC 36: Supreme Court Clarifies Evidentiary Requirements for Breath Tests
The Supreme Court of Canada (SCC) recently issued two decisions that clarify how the Crown proves the preconditions necessary to benefit from the statutory presumption of accuracy under s. 320.31(1) of the Criminal Code in impaired driving cases. This presumption allows breath test results to be considered “conclusive proof” of the accused’s blood alcohol concentration at the time of testing, provided a series of technical preconditions are met.
The core dispute in Rousselle was whether the Crown must call the analyst, or produce the analyst’s certificate, to prove that the alcohol standard used for calibrating the breath testing instrument was certified by an analyst, as required by s. 320.31(1)(a). At trial, the Crown relied solely on the certificate of the qualified technician, which asserted that the standard had been certified. This assertion would otherwise be presumptively inadmissible hearsay, as the qualified technician does not have direct knowledge of the analyst’s certification process. However the SCC dismissed the appeal, holding that the Crown is not required to produce evidence directly from the analyst to prove that the alcohol standard was certified.
The Court found that Parliament intended the 2018 amendments to the evidentiary scheme to maintain the scope of evidence a qualified technician may give, consistent with the historical approach in previous legislative iterations. The purpose of the 2018 amendments was simplification and streamlining of impaired driving prosecutions. Requiring independent evidence from the analyst for this fact would hinder that purpose.
Consequently, the qualified technician’s assertion in their certificate that the system calibration check was conducted using an alcohol standard “certified by an analyst” is sufficient proof of this precondition beyond a reasonable doubt.
The Laroque case, a companion decision, addressed whether, under s. 320.31(1)(a), the Crown must not only satisfy the court that the system calibration check result was within 10% of the target value, but also must actively prove the actual numerical target value of the alcohol standard at trial to trigger the presumption of accuracy.
The SCC dismissed the appeal, holding that the Crown does not need to prove the target value at the time of testing in order to rely on the presumption of accuracy.
Parliament’s intent was not to make the target value itself a statutory precondition. Instead, the precondition requires proof that the qualified technician followed the specific procedure (i.e., that they obtained a result within 10% of the known target value). Requiring proof of the target value would be an unnecessary additional technical requirement inconsistent with Parliament’s goal to simplify and streamline impaired driving prosecutions.
The Court did clarify that the Crown must disclose the target value of the alcohol standard to the accused as part of its mandatory disclosure obligation under s. 320.34(1)(b). The target value is inherently tied to the results of the system calibration check, and without knowing the target value, the accused cannot understand the significance of the result, which is necessary to verify the proper operation of the instrument and challenge the presumption.
4. Kyla’s Insight
These two decisions largely uphold the Crown’s ability to streamline impaired driving prosecutions by relaxing the evidentiary burden required to activate the statutory presumption of accuracy. From a perspective emphasizing strict adherence to evidentiary safeguards and the rights of the accused, the outcomes are problematic because they prioritize efficiency over judicial reliability and rigour.
The majority interpretation undermines fundamental evidentiary rules and statutory safeguards intended to balance the presumption of accuracy with the rights of the accused.
There is a silver lining in the dissent. The dissenting judge, Côté J., argued that evidentiary rules exist to protect the essential truth-seeking function of trials and ensure evidence used for conviction is reliable. By allowing this double hearsay to support an irrebuttable and conclusive presumption of guilt, the Court compromised trial fairness. The majority’s ruling effectively usurps the role of the analyst (who is designated to certify the standard) and makes the analyst’s certificate redundant from an evidentiary standpoint.
On filing the proof of the target value of the alcohol standard, Côté J. believed that if the Crown relies on a statutory shortcut that all but guarantees a conviction, it must rigorously prove the preconditions. Since the target value is the critical comparator for the system calibration check, proving it must be a necessary precondition, not merely a disclosure item. Failing to require proof reduces the Crown’s burden to a paper formality.
Although Parliament aimed for simplification in the 2018 amendments, Côté J. noted the revised statutes also introduced additional, more demanding scientific and technical requirements. The majority’s narrow interpretation ignores this dual purpose of simplification and enhanced reliability by relieving the Crown of these rigorous new safeguards in exchange for a stronger, unqualified presumption of accuracy.
Côté J. emphasised that any interpretation of the evidentiary scheme must be constitutionally compliant, noting that the majority’s interpretation allowing double hearsay evidence likely leads to unconstitutionality and infringes the accused’s right to make full answer and defence. This provides a strong foundation for future Charter-based challenges against the application of these rules.
The majority conceded that if the Crown relies solely on the qualified technician’s certificate (which asserts the alcohol standard was certified by the analyst), the technician likely lacks the knowledge to speak to the certification process during cross-examination. Côté J. highlighted that this procedural weakness means the defence can expose a pointless hearsay exception.
If cross-examination reveals the technician cannot explain the certification or any disclosed defect in the analyst’s information, such as an expired standard, this may be sufficient to raise a reasonable doubt as to whether the precondition was satisfied, potentially leading to an acquittal. The difficulty will be in establishing a foundation for cross-examination.
The dissent reinforces that the Crown bears the risk of relying solely on evidentiary shortcuts. Since the statutory presumption is now conclusive, making conviction nearly inevitable, Côté J.’s analysis provides authority for demanding ironclad adherence to the set technical preconditions. Defence counsel can use this to hold the Crown strictly accountable for compliance with every procedural detail mentioned in s. 320.31(1).
The rulings essentially treat the complex system of breath testing certification like a sealed product guarantee. The majority says that if the Qualified Technician confirms the guarantee is there, that’s enough to trust the machine’s reading, even though the operator didn’t actually verify the guarantee’s contents. The dissent warns that accepting this chain of trust, based on layers of unverified paperwork, effectively hearsay, risks convicting people based on a guarantee without ensuring the foundational scientific inputs were truly accurate, thus weakening the very structure of reliable evidence.
5. Resources
Want to know more about impaired driving and Immediate Roadside Prohibitions in BC? Here are some helpful resources:
- The BC Motor Vehicle Act: https://www.bclaws.gov.bc.ca/civix/document/id/complete/statreg/96318_00
- Criminal Code Offences Relating to Conveyances: https://laws-lois.justice.gc.ca/eng/acts/c-46/page-46.html#h-121277
- CanLII: https://www.canlii.org/
- RoadSafetyBC: https://www2.gov.bc.ca/gov/content/transportation/driving-and-cycling/roadsafetybc
6. Contact Us
The police have their experts. You should have yours.
Charged with impaired driving? Get the lawyer who literally wrote the book on it. Call Kyla Lee at Acumen Law today. Visit our contact form or call 604-685-8889 or email kyla@vancouvercriminallaw.com
7. Featured Firm
Featured Firm: Acumen Law Corporation
Based in Vancouver, Acumen Law Corporation is one of British Columbia’s leading criminal defence firms, recognized across Canada for its work in impaired driving law. The firm’s lawyers have successfully defended thousands of Immediate Roadside Prohibitions, criminal impaired charges, and driving suspensions.
Kyla Lee, a partner at Acumen Law, is widely regarded as a national authority on DUI law. She has authored multiple legal textbooks, teaches DUI defence across North America, and regularly appears in the media explaining developments in driving law.
Acumen Law is known for its deep understanding of both the law and the science behind impaired driving cases. The team approaches every file with meticulous preparation and a commitment to protecting the rights of drivers across BC.
