It's a motorist's responsibility not to hit other road users while overtaking them from the rear. Durp!
In order to meet this responsibility, the motorist must maintain a speed and following distance that will permit them to maneuver around slower road users without hitting them, and they must watch out for such road users. Hurp!
Because motorists cannot be relied upon to meet their responsibility, a cyclist might choose to put lights on his bike, in order to make his presence more conspicuous to lazy, reckless, unvigilant motorists, so that they might avoid hitting him despite their negligence. It is not the cyclist's duty to do so, but if he thinks it might reduce the odds of getting smashed by a car, then the decision to put lights on his bike is a hurpadurp.
If a motorist hits him from behind, it is the motorist's fault, 100%, with or without bike lights and under all driving conditions. This is the diametric opposite of our lawyer friend's contention that if this occurs in the dark, and the cyclist has not assisted motorists in their duty by adding lights to his bike, it is 100% the cyclist's fault.
It's really not hard to decide between these two viewpoints.
While you would arguably be ill advised to stake your life on the vigilance of the American motorist, or even crazy not to avail yourself of lights to assist them in not hitting you, it is still 100% their responsibility not to hit you from behind with their big, stupid death machines.
What is
So HARD
About that?
Oh, but saying this is somehow not inclusive enough (sorry but wtf?) and will cause fewer Americans to buy a bicycle and have fun while burning calories.
I present for your listening pleasure a raspberry sound.