R v Boucher

R. v. Boucher

[2005] SCC 72
Supreme Court of Canada — Deschamps J. (majority), Charron J. (dissenting) | December 2005

Background

Eric Boucher was driving home from a tavern in Montreal at 2:40 a.m. when he encountered a police roadblock on Boulevard La Vérendrye. Instead of continuing straight toward his destination in Ville La Salle, Boucher turned onto Le Caron street — the only escape route from the area — where he was stopped at a secondary roadblock specifically set up to catch drivers trying to avoid the main checkpoint.

Breathalyzer tests showed 93 mg and 92 mg of alcohol per 100 ml of blood. Boucher testified he had consumed only two large beers over two to three hours. A defence expert calculated that someone with Boucher's physical characteristics (28 years old, 175 pounds, 5'11") should have had a blood alcohol level of only 45-60 mg based on that consumption. The Municipal Court judge found Boucher's testimony "not credible" and convicted him, but the Quebec Court of Appeal overturned the conviction.

Issues

1. Can expert opinion evidence rebut the statutory presumption of breathalyzer accuracy if it's based on testimony the judge doesn't believe?
2. What standard must be applied when assessing whether "evidence to the contrary" exists under s. 258(1)(g) of the Criminal Code?

The Credibility vs. Reasonable Doubt Problem

This case exposed a critical distinction that trips up many judges: the difference between *not believing* an accused person and finding their testimony raises *no reasonable doubt*. Under s. 258(1)(g) of the Criminal Code, breathalyzer results are presumed accurate unless there's "evidence to the contrary" that raises a reasonable doubt about their accuracy.

The majority found that if a judge rejects the accused's testimony as not credible, any expert opinion based on that testimony becomes worthless. You can't build expert evidence on a foundation of lies. The court also ruled that the absence of intoxication symptoms (beyond alcohol smell) doesn't help challenge breathalyzer accuracy without evidence of the accused's specific alcohol tolerance — theoretical averages aren't enough.

However, four dissenting judges argued the trial judge made a "fatal error in principle" by asking only whether she *believed* Boucher, rather than whether his testimony might raise a reasonable doubt even if she didn't believe it. As Charron J. put it: "There is a very real and significant difference between believing the accused (which implies that the balance of probabilities favours the accused) and giving the accused the benefit of a reasonable doubt."

Key Takeaway

A judge can disbelieve your testimony but still have reasonable doubt about the prosecution's case — and that doubt should lead to acquittal.

This case shows how challenging breathalyzer evidence requires more than just theoretical expert opinions. You need credible testimony about actual consumption, plus evidence about your specific alcohol tolerance, to successfully rebut the statutory presumption of accuracy.