Abstract: A person, animal, or object in the back seat of a motor vehicle can be presumed to have been inadvertently left there if a back seat access device such as a rear door or seatback of a front seat has been used, followed by the closure of a door lock and not followed by a second usage of the back seat access device. When a person, animal, or object is determined to have been inadvertently locked in the vehicle, an alarm is automatically generated by the vehicle, which notifies the driver, by-standers, and/or an emergency service provider.