Warrants shall not be issued for a person's arrest or a search of their property or person without probable cause. This makes sure that, if a person needs to be apprehended for some reason, the reason itself needs to be good. In addition, when looking at "probable cause," the magistrate weighs the intrusion on the person against the pressing need to execute the search as a way of gaining evidence. The correct answer is the requirement of probable cause to issue a warrant.