A Vancouver firm has launched a class-action lawsuit seeking to overturn nearly two months of impaired driving penalties for B.C. motorists.

Harper Grey LLP alleges police across the province used breathalyzer devices that were improperly calibrated, leading to undue fines, driving prohibitions and vehicle impoundments for drivers who blew in the .05 to .08 blood alcohol content "warn" range last year.

"If they were miscalibrated, as the lawsuit alleges, then people who were actually below the legal limit were still registering a ‘warn' on the device," lawyer Bernard Buettner said.

The suit, filed Thursday, follows a Nov. 19, 2010 announcement by Victoria Police Chief Jamie Graham regarding problem breathalyzer tests.

Graham, as chairman of the B.C. Association of Chiefs of Police traffic safety committee, said 2,200 breathalyzers were being recalled after an RCMP lab test determined some readings were off by as high as one per cent.

"We have to ensure that if you blow a ‘warn' on this instrument you're above 50 milligrams," Graham said. "We think this is important to make this adjustment."

In September, the province enacted tough new drunk driving legislation forcing anyone caught in the "warn" range to face an immediate three-day driving prohibition, a $200 fine and vehicle impoundment.

Harper Grey's suit claims anyone who registered in a "warn" between Sept. 20 and Nov. 19 was potentially penalized in error because roadside breathalyzers don't differentiate between those who blow on the low or high ends of the range.

"The devices don't register a digital reading, they simply register ‘warn,'" Buettner said.

If the action is successful, drivers could be compensated for monetary penalties as well as the cost of driver's licence reinstatement, towing charges and vehicle storage fees.

The B.C. Supreme Court must certify the suit as a class action before it can move forward.

Related: Read the full notice of civil claim