R. v. Collins
33 C.C.C. (3d) 1
Charged with drug use, appellant had been under surveillance by two members of R.C.M.P. Drug Squad. An officer approached her in a pub and said "police officer" and grabbed her by the throat and pulled her down. Officer told her to let go of the object in her hand which was a balloon containing heroin. The officer had heard of this happening before hand and thus it was hearsay.
The trial judge found that the officer did not have reasonable grounds because the evidential basis of suspicion was not admitted following an objection, albeit unfounded, that it was hearsay.