Section 8 of the Canadian Charter of Rights and Freedoms provides that “Everyone has the right to be secure against unreasonable search or seizure.” Court cases have interpreted this provision as meaning that a police officer can only legally conduct a search or seizure on the basis of reasonable and probable grounds for concluding that a crime has been committed. Breath tests are considered searches under the law but they have not been held to be unreasonable since they can be demanded only when there are reasonable and probable grounds for believing the driver is impaired.
Section 9 of the Charter is closely related to Section 8 in providing that “Everyone has the right not to be arbitrarily detained or imprisoned.” Police spot checks for impaired drivers and even random spot checks for a range of purposes including checking for insurance papers and mechanical fitness have been found not to impinge Section 9 for being “demonstrably justified in the interest of public safety” and because driving is a "licensed activity that is subject to regulation and control for the protection of life and property."
Therefore, under the current state of the law, police can randomly stop a vehicle to check the driver’s sobriety but cannot request a breath sample unless they reasonably suspect that the driver is impaired. This may change. The House of Commons justice committee recommended, in a recent report to the Minister of Justice (June 17, 2009) changing the law to permit the police to request a breath test at any time, regardless of whether the driver smells of alcohol or shows signs of impairment.
Reports say that while the Committee chairman Ed Fast conceded it was likely that such a change would be challenged under Section 8 of the Charter, he also said that “the committee concluded that random testing is the most "effective deterrent" available to police….We believe the issue of impaired driving is grave enough in Canada to warrant the government allowing randomized breath testing, and it would be up to the courts to determine whether, in fact, it’s reasonable.”
The committee report also supports tougher sanctions against repeat offenders and against drivers with more than 160 milligrams of alcohol per 100 millilitres of blood or .16-blood alcohol content (BAC), which is over twice the current legal limit of .08 BAC. It did not, however, recommend, as advocated by organizations such as Mothers Against Drunk Driving, lowering the Criminal Code limit to .05 BAC, although most provincial laws (BC included) authorize police to automatically suspend a driver’s licence if the driver’s BAC is above 0.05. Mr. Fast said this was because “such a change would overburden police and prosecutors…by adding 75,000 to 100,000 cases of impaired driving to the justice system each year.” Currently there are about 50,000 cases per year. "That would become untenable, and the whole system would fall apart.” But he did not rule it out altogether saying if resources were made available, this could be reconsidered.