When pot is legal, do fewer teens use it?

"I'm not overly surprised that there's a decrease in use because there's an increased awareness of cannabis amongst parents and guardians and other adults," says Ian Culbert, executive director of the Canadian Public Health Association.

"It is a positive upside of legalization, that we're talking about use and why people use and how you use," says Culbert. "When it's illegal, we don't necessarily have those conversations, we just say, 'It's illegal, it's bad, don't use it, end of conversation.'"