At the moment in Canada, the Highway Safety Code, whether in Quebec or in other provinces, has standards for the use of detection devices. As I mentioned, in the 1960s, an accused was at least allowed to provide a sealed sample so that it could then be tested, as is done with a blood sample. With people whose level of impairment has caused injuries or death, the blood sample is usually put into two vials, one for the defence and one for the prosecution.
Breathalyzers provide, I repeat, an indirect measurement which is bound to give false positives from time to time because it is simply that, one measurement. These days, you can base evidence to the contrary on the person's credibility, but that will no longer be possible if the bill becomes law. In addition, the police have no requirements to maintain or check the devices. For a breathalyzer, there is only one control test, and even it can vary with different scientific approaches. This is 100 mg of alcohol per 100 ml of blood. With other values, we have no idea about the device's performance. But the Crown will have the presumption of accuracy that is, for all intents and purposes, impossible to challenge. If you want to show that the device is not working, you will have no scientific way to do so.