The rules aren't that clear either. For example, defensive driving classes emphasize that there are rules that specify which car has right of way (e.g., at an a

The rules aren't that clear either. For example, defensive driving classes emphasize that there are rules that specify which car has right of way (e.g., at an all-way stop sign), but just because you have the right of way doesn't mean that you should proceed. If another driver disregards your right of way, it's your legal obligation to stop and avoid a crash - you can't blame the crash on the other driver. Also, just because the speed limit sign says 55mph, it doesn't mean that you can always drive at 55mph - there's always an implicit rule that you must consider current road conditions. For example, if you're doing 55 while the highway is covered with ice or there's zero visibility due to fog, a cop can still pull you over for reckless driving. Then, there are clear rules that change suddenly due to geography. For example, in NY State, you can turn right at a red light after coming to a full stop, unless posted otherwise... except within the boundaries of NY City. And NYC has a default speed limit of 25mph, generally slower than in neighboring counties. Rules can also change according to time. Can a self-driving car understand a sign that says "School Zone - Speed limit 15 when light flashing"?