Trafficking is not a term known to the common law. It is a creature of statute and therefore, any definition for a particular jurisdiction must defer to the relevant reference in criminal statutes.
As of 2010, the latter defined trafficking at §2 as:
" ... to sell, administer, give, transfer, transport, send or deliver the (controlled) substance, (or) to sell an authorization to obtain the substance ... otherwise than under the authority of the regulations."
In R v Taylor, the Court of Appeal of British Columbia wrote:
"The gravamen of the charge of trafficking is possession plus the intent or purpose of physically making the hashish available to others, regardless of ownership. The simple fact that it was economic for the purchase price to be collected in advance from the potential users of the narcotic and a bulk purchase made, thereby vesting in such users some claim to ownership and title and even a deemed joint possession by them, does not alter the nature of the physical act of giving, delivering or distributing the narcotic to another or others, which in itself constitutes the offence."
In R v Larson, Justice Branca of the same court added:
"Trafficking does not include the act of buying or accepting from a vendor. The one who buys, accepts or receives a drug might acquire possession of that drug for his own use and/or for the purpose of trafficking as defined in the Narcotic Control Act.
"If he receives possession in one of the ways aforesaid, unless he has a licence he is guilty of unlawful possession of a narcotic."
Compare with this, from Justice Bird in the 1963 case, R v MacDonald:
"Some element or ingredient beyond mere possession is required to constitute trafficking. Unlawful possession is not an essential ingredient of trafficking and the accused person can be in unlawful possession though he be not engaged in trafficking."