SCC Clarifies DUI Breathalyzer Proof for Criminal Defence
Criminal Law ·
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Are you facing an Impaired Driving (DUI) or Over 80 charges? Your criminal defence depends heavily on the Crown’s ability to prove the accuracy of the breathalyzer results. The Supreme Court of Canada (SCC) recently issued two pivotal companion decisions, R. v. Rousselle, 2025 SCC 35 and R. v. Larocque, 2025 SCC 36, which decisively clarify the evidentiary requirements for the Crown under the Criminal Code’s new impaired driving regime (s. 320.31(1)).
These rulings settle crucial debates surrounding the presumption of accuracy for breath tests, confirming the legislature's intent (Bill C-46) to streamline prosecutions. However, they also solidify critical disclosure obligations that your DUI defence lawyer can use to build your case.
Case 1: R. v. Rousselle (2025 SCC 35) - The Analyst Requirement
The central question in Rousselle was whether the Crown must call the analyst or produce their certificate to prove that the alcohol standard used for the instrument’s calibration check was "certified by an analyst," as required by s. 320.31(1)(a).
The SCC’s Holding: The “Evidentiary Shortcut” Remains
The SCC, in a majority decision, confirmed that the Crown is not required to call the analyst or produce the analyst’s certificate at trial. The evidence of the qualified technician—specifically, their official certificate of analysis—is sufficient to satisfy this precondition for the presumption of accuracy to apply.
Key Takeaway: The technician’s certificate, which states the calibration check was done using an alcohol standard "certified by an analyst," is admissible and sufficient proof of that fact. The defence cannot win on the argument that the Crown failed to prove this element merely because the analyst was not called.
Case 2: R. v. Larocque (2025 SCC 36) - Target Value: Proof vs. Disclosure
Decided concurrently, R. v. Larocque addressed a related issue: Does the Crown need to formally prove the specific target value of the alcohol standard in court to rely on the presumption of accuracy?
The target value is the known concentration that the calibration check must fall within 10% of (as per s. 320.31(1)(a)).
The SCC’s Holding: Disclosure is Mandatory, Proof is Not
The Court upheld the conviction, clarifying the distinction between the Crown's obligations:
Disclosure (Mandatory): The Crown must disclose the target value of the alcohol standard to the defence (under s. 320.34(1)(b)). The SCC affirmed that without this figure, the accused cannot properly verify the calibration result.
Proof at Trial (Not Required): The Crown does not need to formally introduce the target value as evidence at trial. The assertion in the qualified technician's certificate that the calibration result was within 10% of the target value is sufficient to meet the evidentiary burden.
Summary for Your Criminal Defence Strategy
These two decisions affirm that the new evidentiary scheme for impaired driving is robust. However, they also solidify key defence strategies focusing on a meticulous forensic review. Following Rousselle, while the Crown does not need to call the analyst, your criminal defence lawyer should scrutinize the qualified technician's certificate and processes for any potential inaccuracies. Similarly, with Larocque, although the Crown isn't required to prove the target value at trial, they must disclose it to the defence. This disclosure is a critical tool, allowing your lawyer to independently verify the calibration accuracy and raise reasonable doubt if any discrepancies exist regarding the breathalyzer's proper functioning.
If you are facing a DUI charge, it is crucial to retain a criminal defence lawyer who understands these complex evidentiary rules. The path to an acquittal based on technical flaws has narrowed, making detailed scrutiny of the calibration records and challenging the qualified technician’s assumptions the most critical focus of your defence.
Do not assume the "presumption of accuracy" is unbeatable. Contact our firm today for a confidential consultation to discuss the breathalyzer evidence in your case.
DISCLAIMER:
The information provided in this blog is for general informational purposes only and does not constitute legal advice. No attorney-client relationship is established through this writing. You should consult with a qualified attorney for advice tailored to your specific situation. The lawyer and their firm disclaim any liability arising from reliance on this blog or any other content on this website.
Questions about this topic? See our page on impaired driving and refusal charges in Mississauga, or call (289) 652-0529.
Frequently Asked Questions
What is the main issue decided in R. v. Rousselle and R. v. Larocque?
Both SCC decisions deal with the presumption of accuracy for breathalyzer results under the Criminal Code (s. 320.31(1)). They specifically clarify what evidence the Crown must provide regarding the alcohol standard used to calibrate the testing instrument in an Impaired Driving case.
Does the Crown now have to call the analyst in DUI cases?
No. In R. v. Rousselle, the SCC confirmed that the Crown does not need to call the analyst or produce the analyst's certificate. The qualified technician's certificate is sufficient proof that the alcohol standard used for calibration was properly "certified by an analyst."
What is the significance of the "target value" after the Larocque decision?
The target value (the expected reading for the alcohol standard) is now confirmed as an item the Crown must disclose to the defence, as it is necessary for the accused to verify the calibration check result. However, the Crown does not have to formally prove the target value at trial to rely on the presumption of accuracy.
How do these decisions impact my criminal defence against a DUI charge?
These cases confirm that the evidentiary shortcuts are valid, but they reinforce the Crown's disclosure obligation for critical information like the target value. Your criminal defence lawyer must use this disclosed information to scrutinize the qualified technician's procedures and calculations, looking for any evidence of malfunction or error that can raise a reasonable doubt.