The B.C. Supreme Court is expected to rule Wednesday on whether the province's tough new drunk-driving law violates constitutional rights.

Described as the strictest impaired driving law in Canada, the B.C. Motor Vehicle Act's automatic roadside driving prohibition clause allows police to issue roadside suspensions, impound cars and levy fines in the hundreds of dollars for drivers with a blood alcohol level of 0.05 or higher.

The judge will rule whether the province overstepped its authority by enacting the law, which would render it constitutionally void.

The judge could find that B.C.'s new law is in conflict with existing federal criminal law relating to drunk driving and blood alcohol levels of 0.08 or higher.

The judge could also find that B.C.'s law leads to a violation of the Charter of Rights and Freedoms because the law gives too much power to the roadside police and allows for no appeal mechanism.

The decision would have immediate implications for other provinces in the process of enacting similar legislation.

Last week, the Alberta legislature tabled a bill that would allow police to immediately suspend the licence of anyone caught driving with blood alcohol content over 0.05. The penalties include the power to keep licence suspensions in place for people caught with more than 0.08 of blood alcohol content until their cases are dealt with in court.

Alberta's solicitor general had previously said that the province might not copy B.C.'s law, in which police can immediately suspend a licence for three days and impound the vehicle on a first offence if the driver blows over 0.05 per cent. Alberta presently makes use of the criminal code bar of 0.08 per cent blood alcohol level.

Unpopular, but effective

B.C. defence lawyers have derided the law, and bar owners and restaurateurs have complained it scares away patrons or impacts their money.

The government promised to revisit the legislation or ease up on the extent to which the regulations were being applied. But it backed off from those assurances when statistics started to show the law was saving lives.

Last week, the government said the number of deaths in alcohol-related crashes had dropped 40 per cent in a year.

But some lawyers have fought back in court, arguing the province is intruding on federal jurisdiction, since the Criminal Code sets the blood alcohol limit at 0.08.

The case the court will rule on was prompted by a petition filed by Philip A. Riddell, lawyer for Aman Preet Sivia, who was stopped about 10 days after the law came into effect in September 2010.

Sivia was found to be in excess of the 0.05 blood alcohol restriction and was issued a driving prohibition at the roadside by a police officer.

Sivia applied to the Superintendent of Motor Vehicles for a review of the officers decision, but was denied.

With files from the CBC's Jeff Davies and Stephen Smart