That is a very good question. Legally, trafficking drugs means more than just selling drugs. Under section 2 of the The Controlled Drugs and Substance Act, it reads:
“traffic” means, in respect of a substance included in any of Schedules I to IV,
(a) to sell, administer, give, transfer, transport, send or deliver the substance,
(b) to sell an authorization to obtain the substance, or
(c) to offer to do anything mentioned in paragraph (a) or (b),
otherwise than under the authority of the regulations.
You can be charged with a criminal offence not just for selling drugs, but also for sharing them, just among friends.
*Note: The information on this page is for general knowledge and is not legal advice.