If a jury finds that the arresting officer had reasonable cause to make the arrest, what is the law around this question?

If, as appears likely, the question shall again be presented whether or not the arresting officers had reasonable cause to make the arrest, its determination should be made by the trial court and not left in whole or part to the jury. People v. Gorg, 1955, 45 Cal.2d 776, 780-781, 291 P.2d 469, 471-472. The testimony of the officer that an informant told him that the defendants were narcotic users, although properly received on the issue of the legality of the arrest, should not have been allowed to reach the ears of the jurors.