And what if the passenger doesn't want the car to stop—can she override the command, or does the police officer have ultimate control?
No... the driver already surrendered ultimate control to the car by choosing a self-driving vehicle, and
I expect the vehicle to obey the law, Even over the driver's wishes, which says that citizens must follow
a lawful official's orders, unless following the order clearly violates civil rights or creates an immediate safety hazard for
themselves or another person.
Being required to stop your vehicle and pull over to be detained is a legal reasonable order,
So long as the car can legitimate establish the authority of the person directing.
Your self-driving car should take some precautions, in case the person gesturing your car to stop is
a crook in disguise.
I see a possibility of allowing the driver to override a gesture, if the driver has
the autonomous vehicle place a 911 call and hold the horn down.
The driver's picture identity and vehicle info will be automatically transmitted.