Nova Scotia (Canada) passed a bylaw (starts Nov 16th) that made it mandatory for all stores selling game to follow the ESRB ratings. Mature is 17+ etc.
This is a cross Canada initiative (not mandatory) that has also been put in place:
http://www.esrb.org/about_updates.asp
Canadian Retailers and Video Gaming Industry Launch National Ratings Education and Enforcement Program (October 14th, 2004)
Canadian retailers and the computer and video game industry today announced the launch of a new countrywide "Commitment to Parents" initiative beginning this holiday season to help parents ensure the games they buy for their children are appropriate for their households.
Commitment to Parents is an industry-led voluntary initiative designed to limit the sale or rental of games to children that are meant for older teenagers and adults. It achieves this through a combination of educating consumers about the video game rating system and point-of-purchase controls.
Today's announcement was made by Retail Council of Canada (RCC), the Entertainment Software Association of Canada (ESA Canada) and the Entertainment Software Rating Board (ESRB) at news conferences in Winnipeg, Halifax and Toronto. The program has been in operation in British Columbia since 2001.
Participating retailers have agreed not to sell or rent "M"- rated (Mature) games to customers under the age of 17, or games rated "AO" (Adults Only) to customers under the age of 18. These retailers are also displaying store signs which advise customers of their participation in the program and promote awareness and understanding of the ESRB rating system.
"This initiative is an extension of retailers' commitment to customer service," said Diane J. Brisebois, President and CEO of Retail Council of Canada. "When parents enter a participating retail store they can feel confident that the retailer is working on their behalf to ensure the video games their children buy or rent are suitable for their age."
Commitment to Parents participating retailers to date include: Hudson's Bay Company retail outlets the Bay and Zellers, Best Buy, Blockbuster Canada, EB Games, Future Shop, RadioShack, Rogers Video, Toys 'R' Us, and Wal-Mart.