Bill C-45 prohibits distributing, providing, or selling cannabis to any young person under the age of 18. A young person between the ages of 12 and 17 would not be criminalized for possessing five grams or less. They could also share it, without being criminalized, with another youth the same age. The age of criminal responsibility is 12 to below 18 under the Youth Criminal Justice Act , so any adult who gives it to any young person is criminalized, but a youth is dealt with differently.
On September 11th, 2017. See this statement in context.