In what circumstances will police officers be entitled to believe a purchase and sale transaction occurred between the suspects?

"In each case the officers were entitled to believe a purchase and sale transaction had occurred between the suspects. There is no material difference in the circumstances, in Cunha and the case at bench, respecting the existence of such a transaction." (People v. Knisely, supra, 64 Cal.App.3d at p. 114, 134 Cal.Rptr. 269.)

On the other hand, an officer's observations of the exchange of money for an identifiable object played a significant role in the finding of reasonable cause for arrest on a narcotics charge in People v. Garrett (1972) 29 Cal.App.3d 535, 104 Cal.Rptr. 829.