An approved screening device demand can be made "if a peace officer has reasonable grounds to suspect that a person has alcohol or a drug in their body and that the person has, within the preceding three hours, operated a motor vehicle or vessel, operated or assisted in the operation of an aircraft or railway equipment or had the care or control of a motor vehicle. . . " [emphasis added]
Knowing the definition of "reasonable suspicion" is just as important for peace officers investigating possible impaired drivers at the roadside as it is in "sniffer dog" investigations. Reviewing the Chehil and MacKenzie cases is highly recommended. The "in their body" and "within the preceding three hours" requirements are highlighted above as it is not uncommon for counsel to see files where a peace officer has not turned his or her mind to those two requirements for an approved screening device demand.