Legal Question in Criminal Law in Canada

Re: the police failed to issue me a ticket. could I still be charged?

The fact that the police didn't give you a ticket on the scene doesn't help you. The police can always issue and serve a summons for you to appear in court. Their intention was to get a bigger catch and the police were holding the possibility of a charge against you as an incentive for you to give up somebody else.

Essentially there is nothing wrong with this practice. Moreover, in the circumstances of this case, the police do not need your confession in order get to get a conviction. The marijuana was on your person and so unless you didn't know it was there and what it was, there is no defence to the charge. That is of course subject to a proviso that if the search was an unreasonable search and seizure--which likely it was, although you would have to prove it at trial--you can bring a Charter application to exclude the evidence.

The police made you an offer. If the time for accepting the offer has not passed and you accept the offer, then the police cannot charge you. Implicitly, the offer requires that you provide truthful information and that you co-operate in the investigation, for instance, by testifying truthfully at the trial of the person you are exposing. The deal should not require that the other person actually ends up being convicted. If you choose to co-operate, but do not complete your end of the bargain, you might be charged with the possession or may even face another charge such as obstruct justice. On the other hand, should the police renege on their promises and charge you anyway, you would have good grounds for getting the case thrown out.

Remember however, that you are under no obligation to co-operate in the first place. Often the decision not to co-operate with the police is reasonable because of the fear of reprisal.