Supreme Court of Canada upholds impaired driving convictions based on breath tests

OTTAWA — The Supreme Court of Canada has upheld impaired driving convictions in two cases, saying criminal law amendments enacted in 2018 were intended to streamline prosecutions based on breath test results.

The related decisions from the top court Friday clarify the evidentiary scheme for proving blood alcohol concentration in impaired driving cases under the Criminal Code.

In each case, the Supreme Court looked at whether the New Brunswick Court of Appeal erred in interpreting what the Crown must prove to satisfy a presumption that breath test results are accurate.

The law requires a breath machine calibration check, the result of which must fall within a particular range.

In one case, the Supreme Court examined the evidence needed to prove a breath machine has successfully gone through a calibration check.

In the other case, the court considered what must be established to use the results of a breath test in court.

This report by The Canadian Press was first published Nov. 14, 2025.