What is the test for having reasonable and probable grounds?

Cory J. in R v. Storrey, 1990 CanLII 125 (SCC), [1990] 1 S.C.R. 241, summarized what having reasonable and probable grounds entails at 250-251: In summary then, the Criminal Code requires that an arresting officer must subjectively have reasonable and probable grounds on which to base the arrest. Those grounds must, in addition, be justifiable from an objective point of view. That is to say, a reasonable person placed in the position of the officer must be able to conclude that there were indeed reasonable and probable grounds for the arrest. On the other hand, the police need not demonstrate anything more than reasonable and probable grounds. Specifically they are not required to establish a prima facie case for conviction before making the arrest.