Canadian Criminal Law/Trafficking
Section 2 of the Controlled Drugs and Substances Act states:
2. (1) In this Act,
“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.
Offer to Sell
Trafficking by offer under s. 2(2)(c) only requires that the crown prove an intent to make the offer. It is not necessary to prove that the accused had an intent to follow through with the offer. As such, there is no need to prove that the accused had drugs on themselves at the time or was capable of fulfilling the request.
R v Mamchur,  3 WWR 481 (SKCA) at p. 483
R v Jones, (1988) 74 Sask R. 4 (SKCA) at 10
R. v. Campbell, 1999 CanLII 676 (SCC),  1 S.C.R. 565 at 25
R. v. Murdock 2003 CanLII 4306 (ON CA), (2003), 176 C.C.C. (3d) 232 at 14
R v Crain, 2012 SKCA 8
e.g. R. v. Petrie,  O.W.N. 601 (C.A.) -- drugs offered weren’t available;
R. v. Murdock, supra -- offer was withdrawn
R. v. Sherman,  5 W.W.R. 283 (B.C.C.A.) -- offer was made for purpose of ripping buyer off
R. v. Reid 1996 CanLII 5213, (1996), 155 N.S.R. (2d) 368 (NSCA) -- no evidence that drugs were even available to seller
R. v. Brown (1953), 9 W.W.R. (N.S.) 701 (B.C.C.A.) -- drugs not on the seller
Opinion Evidence on Trafficking
To prove that someone was in possession of a controlled substance for the purpose of trafficking, the Crown must call expert evidence to given an opinion that the circumstances allow for the inference that the possessor intended to traffick.
See also: Canadian Criminal Evidence/Opinion/Expert Evidence for details on the law of expert evidence.
Evidence of Intent
Amount of drugs
Trafficking can be inferred where the quantity/purity/value of drugs is high.
Where an accused is a user of drugs, there may be evidence suggestive that the drugs found in their possession may be consistent with personal use as opposed to trafficking. The amounts required to maintain the addiction and the habits of typical users are relevant. Either party is permitted to lead evidence concerning typical use, however, this usually takes the form of expert evidence.
The amount of drugs alone cannot be used to establish trafficking.
Marijuana amounts in the range of 3 pounds have been found to be unreasonable to be considered consumable for personal use. 
Large quantities of unexplained wealth can allow a judge to lead to the conclusion of trafficking. This is particularly true where cash is in small denominations and is found near drugs.
Where packaging is found this may allow a judge to infer an intent to traffick. Packaging in numerous quantities, such as numerous small baggies, can create such an inference. 
R. v. Le, 2001 BCCA 658
R. v. Adelberg, 2001 BCCA 637
R. v. L'Huillier, 1997 CanLII 9606 (NB Q.B.)
R. v. Falahatchian, 1995 CanLII 941 (ON C.A.)
R. v. Naugler, 1994 ABCA 110
- R. v. Petavel, 2006 BCSC 1931
R. v. McCallum 2006 SKQB 287 (CanLII), (2006), 281 Sask.R. 272 at 28
R. v. Mehari, 2009 ABPC 217 at 7
- R. v. Brophy (W.) (1971), 3 N.B.R.(2d) 594 (CA)
R. v. Alberts, 1999 CanLII 2246 (ON C.A.)
R. v. Le, 2001 BCCA 694
R. v. Scott, 2003 CanLII 27446 (ON S.C.)
R. v. Kwok, 2002 BCCA 177
R. v. Petavel, 2006 BCSC 1931
A Dial-a-Dope operation is the manner in which drugs are often distributed to their customers. The seller and buyer will contact each other by phone and arrange to make an exchange at a pre-determined location.
The Crown will often adduce evidence to argue that the evidence suggests that such an operation was undertaken. This is determined by expert opinion of the evidence suggestive of such an operation.
Several cases have considered the methods of a dial-a-dope operation.