Red light crash: who is at fault
You believe the other driver ran the light, but you are not sure how to prove it.
Running a red light is strong evidence of fault, since it is both a traffic offence and a clear act of carelessness at a controlled junction. The dispute is rarely about the rule itself. It is almost always about which light each driver actually had, especially around an amber change. For the general approach, see who is at fault in a crash.
The typical facts in this crash
Two vehicles collide at a signal-controlled junction, and each driver is convinced the light was in their favour. Impact is often broadside, since the crossing vehicle is usually hit on its side. This is a specific version of a junction collision, decided mainly by what the signal showed.
How fault is usually assessed
A court looks at what each traffic light actually showed at the moment of impact, not simply which driver claims to remember it correctly. A driver who enters on a clear red carries heavy responsibility, while a genuine amber-light dispute can be closer and needs stronger evidence to resolve.
The evidence that decides a red-light dispute
- Dashcam footage that captures the light colour and the moment of entry.
- CCTV from the junction itself or from nearby buildings.
- The pattern and side of the damage, showing who was broadsided.
- Witnesses positioned to see the signal, not just the crash.
- The police report’s own account of the light sequence at that junction.
A late police report is itself an offence and can weaken your position later, so report within 24 hours wherever possible.[2] The police report after an accident and dashcam, photo and video evidence explain how to use this evidence well.
Contributory negligence at a signalised junction
Speed matters here too. A driver who had the correct light but was travelling well beyond what was safe for the junction can still share some responsibility, and a rider without a helmet can have their own compensation reduced separately.[1] Contributory negligence explained covers this without predicting a fixed outcome.
What to do at the scene and after
Do not assume the traffic light will always be caught on a public camera. Treat your own dashcam and any witnesses as your main evidence. A road accident claim explains what happens once liability is disputed and needs to be resolved.
Common questions
How is a red-light crash actually proven, since lights change so fast?
Mostly through dashcam footage, CCTV, and witnesses who saw the signal rather than just the impact. The police report also records what officers found at the scene, which supports whichever account the other evidence backs up.
What if it was an amber light, not a clear red?
Amber-light disputes are genuinely harder, since both drivers may honestly believe they had the right to proceed. This is exactly where independent footage matters most, because personal recollection alone rarely settles it.
Does a traffic summons for running the light guarantee I win my claim?
It helps, but it is not the same question. A summons deals with the traffic offence, while your civil claim still needs to show the crash caused your specific injuries and losses.
I was speeding but had the correct light, can I still be blamed?
Possibly, in part. A driver with the right of way can still share some responsibility if their speed was unsafe for the junction, though the driver who ran the light usually carries the greater share.
Sources
- Civil Law Act 1956, s.12 (Attorney General's Chambers) (accessed 2026-09-22)
- Road Transport Act 1987, s.52 (Ministry of Transport) (accessed 2026-09-22)