The B.C. Supreme Court has certified a class-action lawsuit against Mazda Canada over an alleged door-lock defect.

The lawsuit was launched by B.C. resident Alisha Koubi, who claims she leased a Mazda3 in September 2006 and later learned the defect allows car thieves to break in with nothing more than a soft shoulder bump to the driver's side door.

Koubi's car was never actually broken into, but she says Mazda sold her a vehicle it knew was unfit.

Mazda's lawyers argued in court that the company took measures to deal with the problem as soon as it learned of break-ins, but didn't want to publicize the issue because it could have put more car owners at risk.

Koubi's lawyer has been contacted by 128 other Mazda3 drivers who allege they've suffered a loss as a result of the door-lock defect. Mazda Canada estimates nearly 18,000 of the vehicles were sold in B.C. for the model years 2004 to 2007 with the same lock mechanism.

Justice D. Jane Dardi issued her ruling Thursday but a trial date has not yet been set. Similar lawsuits have been launched against Mazda Canada in Ontario and Quebec.