This question is prompted by me sitting at a green light today while multiple people streamed through from the opposite direction, turning to their left, against a red turn arrow. (Throughout this question, assume right-side traffic, as in North America, and no one-way streets.)
If I have a green light and enter a clear intersection, then it would seem obvious that an unseen red light runner on the cross-street, coming from my left/right, would be at 100% fault for hitting me and causing an accident.
But suppose I am sitting at an intersection waiting to go straight through and facing a red light, while traffic on the opposite side of the intersection has a green left-turn arrow, and are turning across my intended path.
The left-turning cars lose their green arrow, get a red arrow (or red light, or other signal that they no longer have the right-of-way), and I now get a green light, but the line of cars still continues, turning left and driving across in front of me, running their red left-turn arrow.
If I now enter the intersection and an accident occurs, who is at fault? Is it the opposing car for obviously running a red left-turn arrow? Or is it me for performing an unsafe action, even though I had a green light?
I can imagine that I would be allocated some/all fault if I can see all these cars driving in front of me but still enter the intersection, yet at other times there is some car wanting to turn that is lagging all of the others and it enters the intersection after I have already entered it (and I don't see them coming, making it like the original red light runner scenario I mentioned above). In such a case I would expect the turning car to be at fault. So there would seem to be an area where fault allocation moves from one driver to another.
I'm mainly interested in US interpretations, but any jurisdiction would be interesting to me.