Challenge to impaired-driving laws

A 2008 Criminal Code amendment is being challenged on the grounds that it imposes a reverse onus to disprove their guilt in court upon those who test above the legal limit on a Breathalyzer.
This was challenged in a case recently before the Brampton Provincial Court. The defendant was found sleeping in his car early one morning, and was charged with having care and control of a motor vehicle while impaired. His blood alcohol content was twice tested, and found to be over the legal limit both times. The Criminal Code deems this to be conclusive proof of blood alcohol levels.

In order to disprove his guilt, the defendant would have had to provide evidence that the machine with which he was tested had malfunctioned, and that the defendant’s blood alcohol content was within the legal limit – the defence was unable to do so. While there were witnesses able to testify on his behalf, this testimony alone is not considered sufficient to raise reasonable doubt in cases where the defendant is found to have a blood alcohol concentration above the legal limit.
The argument that machines may malfunction, without the knowledge of the officer operating it, is not without controversy. Dr. Robert Langille, a toxicologist at the Centre for Forensic Sciences in Toronto, believes that if the machine malfunctions the officer will be aware of it. He stated that there are stringent testing procedures for the machines used in Ontario.
As for the question of whether or not the law is constitutional, Justice Bruce Duncan held that it was. He stated in his judgment that, “There is probably no requirement that the law provide for any defence at all, much less one that is easily attainable.”
The case is on appeal before the Superior Court of Ontario.