The banks had sought leave to appeal for a lower court decision allowing the cases, but the Supreme Court dismissed the application.
Laywers David O'Connor and Louis Sokolov who represent Cindy Fulawka and Dara Fresco said their clients were pleased that the cases could now move forward on their merits.
The lawsuits allege thousands of workers were denied overtime pay even though they were assigned more work than could be completed within their standard hours.
A lower court had denied class action status to the CIBC (TSX:CM) case, while a different court had allowed class action status be granted to the Scotiabank (TSX:BNS) lawsuit.
However, the Ontario Court of Appeal felt both cases, which have not been proven in court, should be handled the same way and ruled they could go ahead.
Both CIBC and Scotiabank noted the decision by the top court was not on the merits of the lawsuits or the banks' overtime policies, but rather the class-action certification process.
"This is just another step in what is a multi-stage legal process and CIBC will defend its position vigorously in the subsequent trial on common issues related to this case," CIBC spokesman Kevin Dove said.
Scotiabank spokeswoman Ann DeRabbie said the bank was disappointed by the court's decision.
"We're confident that employee policies have been fairly applied and consistently applied," she said.
In the CIBC case, Fresco filed a lawsuit in June 2007 on behalf of more than 31,000 tellers and other front-line customer service employees working at more than 1,000 CIBC branches across Canada, including assistant branch managers, financial service representatives, financial service associates and branch ambassadors.
Fulawka, a personal banking representative at Scotiabank, filed her class-action lawsuit against the bank in December 2007 seeking to represent some 5,000 Scotiabank personal or senior bankers, financial advisers and small business account managers.
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