Challenge
Police charged Ms. K with operating over 80 mg after she provided breath samples at a Toronto police division. The readings sat marginally over the legal limit.
The defence examined whether the approved instrument had been properly maintained and calibrated in accordance with regulatory standards.
Disclosure revealed:
- Incomplete maintenance logs
- Gaps in annual inspection documentation
- Unclear notation about the simulator solution used
A reading just over the line leaves little margin for error, which is why how weight, food and time change your BAC matters so much in these cases.
Our Process
- Planning the case. We conducted a line-by-line review of calibration and maintenance records and examined the breath technician’s qualifications and compliance with required testing protocols.
- Technical review. We compared the documentation against the statutory and regulatory requirements governing approved instruments, and we identified and analyzed every inconsistency or missing record for its impact.
- Cross-examination. Under questioning, the technician had to explain specific log entries and maintenance intervals. His uncertainty about those records raised reliability concerns.
- Reliability argument. We argued that breath readings are only as reliable as the procedures behind them. When the Crown cannot clearly establish foundational compliance, the presumption of accuracy may fall away.
Result
The court found that the Crown failed to establish the necessary evidentiary foundation for the breath readings. Without reliable breath evidence, the prosecution could not prove the over 80 offence. The court acquitted Ms. K.
Our explainer on what affects how long alcohol shows on a breathalyzer covers the science behind these readings, and our DUI defence guide explains how instrument records fit into a breath case.
Every case is different, and past results do not predict future outcomes.