@Hari_Seldon got it right. In Canada, if a law is enacted in both English and French, then both language versions are equally authoritative. The French version is not a “translation” of the law; it is the law, equal in status to the English version.
There are, of course, rules of construction which have evolved to deal with cases where the two versions may not agree. One approach, and the narrowest, is the “equal common content” guide. If one version of the law has a much narrower apparent meaning than the other, then the narrow version governs, because that is the common content of both versions.
There is another approach, though, (name escapes me at the moment) where both versions are considered to modify the other. That’s because it’s not very common to encounter a version that is clearly narrower than the other. What’s more common, as in this case, is that the wording in one version may be more ambiguous than the other.
At first glance, it may be that in English, “vessel” means a large boat, as argued by the accused. However, if some dictionaries use that meaning, and other dictionaries use a different meaning that fits with the meaning in the other language, then that points the courts towards the less ambiguous version, to reach an identical interpretation.
For example, noodling around on the internet, I find that Oxford and Cambridge both define “vessel” as “large boat”. That supports the accused’s argument.
However, I’ve found another source, don’t know how reputable, that says this:
That supports the Crown’s interpretation. The ambiguity between the different English meanings of “vessel” can be resolved by comparing it to the French version to resolve the ambiguity.
Still another approach is to consider the purpose of the provision in question. For example, in this case, does it make sense to include “canoes” in the prohibition on impaired operation? The accused apparently argued that it doesn’t, because there is no one person in control of the canoe, so it’s different from other vehicles. But, if both persons have a degree of control, both could endanger the vessel’s operation, so wouldn’t it mean that both could potentially be criminally liable if operating it while impaired? For example, the impaired offence applies to pilots operating airplanes. I’ve never seen a suggestion that the copilot can come on board drunk and escape criminal liability because the pilot was sober.
And then, in the specific case of canoes, they take skill and balance. One impaired person could endanger the other person in the canoe, and that suggests that the criminal prohibition should apply.
For instance, if a guy named Harrison and his buddy Tyler go out canoeing, and Harrison is blotto, it could easily be a case where he tips the canoe and Tyler too.