Here’s the hypothetical:
Middle of the night, no witnesses, no other cars. You drive through an intersection where you have a green light, and someone runs the red going the other way and hits you.
How could the police tell who ran the light and was at fault?
Unless there’s a traffic light camera, I can see no way to determine fault if the guilty party is determined to lie about it.
The guy with the banged up front end.
That won’t work. Both cars are acting identically, as if they have the green light, so who t-bones who is just a matter of timing.
Well, if both cars hit each other at the same exact time (both front corners of the cars getting hit), and if one guy was assholish enough to lie about it, I’m sure forensics could figure out something. I’d be too pist if that happened to me.
How could forensics determine who ran the light? The incidence of damages would be the same no matter who ran the light.
This happened to me once.
I pulled up to a red light and stopped. Upon entering the intersection, a car going perpendicular to me slammed into me, pushing me into a telephone, totaling my little car.
The guy who slammed into me swore up and down that he didn’t run a red light, but I knew he had. I was too stunned to argue, though. The police officer showed up and took our accounts of the story, and then wrote a ticket for the guy. Who was down right pissed.
“Wait a minute!” he yelled. “How do you know I was at fault?”
The police officer was quite familiar with the area, and knew that people often speed through the traffic light in the direction the guy was coming from (the light appears kinda abruptly). The guy was from out of town, so he was unfamiliar with that intersection (I lived right on the corner of the intersection, so I had “hometown” advantage). Her decision wasn’t based on scientific principles. Just common sense.
In an uncontrolled intersection (or in this case, where there are no witnesses), the person coming from the right will be assumed to have the right of way, UNLESS the other car is in the intersection first. To determine that is a simple matter of looking at the damage. If he hit you aft of the midpoint of your car, you were clearly in the intersection first, which would seem to indicate you had the green light.
Never pay a ticket before talking first to your insurance agent. I learned it the hard way.
Nonsense. The person with the green light has the “right of way.” If you approach a green light, however, and see someone crashing the red, there would be a degree of negligence on your part. If he were going so fast that you couldn’t see him in the intersection, you weren’t negligent, and where he hits your car would depend upon the speeds of the cars.
because the guy running the red would presumably brake once he saw he was running through the red.
The green guy probably would and would try to swerve.
Behavioral psychology has its uses 
You obviously don’t study driving behavior in Baltimore. The realization that you might run a red light in this town is usually a precursor to flooring the accelerator.
I don’t think there’s a definitive answer to this question. The guy running the red light is definitely at fault, but what does that have to do with who gets stuck with the blame in this situation?
A long time ago, between Christmas and New Years I was driving down Lankersheim Blvd. in Los Angeles with my wife and a friend. I glanced in the rear view mirror and saw a black and white pull onto the boulevard from a side street. Now I maintain it is impossible to drive rationally if a police car is behind you. I drove very correctly and kept glancing in the mirror to keep track of the cop. As I came to an intersection I glanced back and then noticed a car blunder into the intersection from my right. I glanced back again to see if the cop was going to notice this stupid idiot who was cutting me off. Then it regisered that my friend was quiety saying, “Red light, red light, …”
I went on through and pulled over to the right curb and the cop stopped for the light and just sat there. I couldn’t believe he hadn’t seen me, but I finally put the car in gear and slowly pulled out at which time the red lights came on so I stopped.
A very nice police officer (this was in the days of Chief William H. Parker) came up and asked for the usual documents and asked if I knew what I had done. I told him yes and I was sorry. He looked at my driver’s license and asked if my current address was still Podunk, CA. When I told him it was he said, “Well, Mr. Simmons, you probably don’t have too many traffic signals in Podunk, but we’ve got a lot of them in Los Angeles. Watch a lot more carefully in the future.”
And he got back in his unit and drove off.
Does anyone on this board actually read the goddamn posts anymore?
A large proportion of urban traffic lights are controlled by “computers downtown” – meaning some sort of device that manages them, on a standard schedule unless overridden, as for example to give an ambulance or fire truck a clear right of way.
In such a circumstance as this, if the exact time of the accident can be pinpointed somehow, it would definitely be worth asking if the traffic light is controlled by a computer and what that computer says about which way had the green light at the time of the accident.
Walk signals would probably mess with that schedule, Polycarp. It seems like it would be quite unreliable.
Unless the light just turned I can’t see a way the damage could imply who ran the light. If the light just turned, the car with the right of way would have just started moving, definitely changing the way the impact happens. But if the light has been green already, and both parties are simply driving at approximately equal speeds, I can’t for the life of me think of a way to tell–without witnesses. 
A sort of science called speed skid. The length of the skids, placement of the cars, amount of damage can indicate the speeds of the cars. Reaction time to hitting the brakes is approximatly .75 second; some calculations and you get a clue as to what happened.
I found out by getting hit by a guy who blew a red light; and I got the ticket. He came up with a lying witness. I was sunk, until a lady contacted me who had seen it all and was upset about the injustice. With her testimony and the help of a CHP speed skid specialist, I was cleared.
Now the aggrivation. We both had Farmers Insurance. The insurance company refused to pay my damages. I got a lawyer, sued for a bunch and they paid up more than my damages by enough to also pay off the lawyer. Then I switched to State Farm where I’ve dutifully paid them some $3K-4K/year for car and house insurance for 30 years; with no claims.
So Farmers got to pay me more in the first place, and lost out on some $100,000 in payments I’ve since paid to State Farm.
Sharp move, Farmers.
The traffic preemptors around here are locally controlled, e.g. timing is handled by the local signal box. If an emergency vehicle preempts the signal, a time stamp is recorded along with the ID of the vehicle which caused the preemption, but other than that, there is no central data repository.
We’ve been after PENNDOT to synchronize lights on major arteries, but I fear the 17 year cicadas will make their return first.
There is no uncontestible way this can be done given the situation you describe.
An example above cited “common sense.” And if the cop involved has any, then MAYBE some justice will happen. More often I see police reports that have no decision in the absence of evidence.
Insurance companies will assign fault using a combination of facts listed in a police report (tickets, etc.) as well as taking a look at where the damage appears on each car and how severe that damage is. Most traffic cops don’t get into this kind of detail–they got robbers to chase and donuts to devour.
Outside of evidence & witnesses, we look at any statutes that require certain actions over an above what the traffic light says. Laws that say things like “you have to try & avoid an accident, even if you have the right of way.” The best example of this is a common statute that requires standing traffic to allow other cars to clear an intersection before proceeding. This means that when someone creeps into an intersection on a green light (no arrow) to make a left turn and he is unable to complete the turn before his light goes red, you can not stomp on the gas when you get your green and blow him out.
In most states, a percent of liability(fault) can be assigned with either or both cars in the OP scenario depending on things like: what evasive action was available to either car, and how much time was each likely to have had to take such action? If the accident is a “broadside,” how many lanes did the car with front-end damage have to cross before impact? If the impact on the side-damaged car is toward the front of the car, it can be assumed the other driver had little time to respond. If it is toward the rear, then the other driver may have missed an opportunity to avoid the crash.
In any event, proving any such divisions of fault will depend on the skill of either party’s representative to present his case. The OP’s scenario will almost always result in a 50/50 liability decision where nobody is liable for the other party’s damages. Sucks if you had the right of way. Be careful out there!