A driver in car A is driving down a road and encounters the following that forces a hard brake:

  1. A branch or electrical line dropping on the roadway.
  2. A dog running out into the roadway, as per driver A. Disputed by driver B. (Brake check)
  3. A ball rolling into the roadway.

A driver in car B following is unable to stop and an accident ensues.

Would all the above scenarios result in driver of car B being found most blamable? United States, no-fault

  • 2
    In all cases described, Driver B was following too closing for the conditions. If he had been following at 3 seconds, he would've had sufficient time to react.
    – abelenky
    Commented May 22, 2023 at 19:49
  • "United States, no-fault" In a "no fault" automobile insurance regime, the fault of parties to minor accidents doesn't matter, you always have your own insurance company cover those losses and can't sue. But it isn't clear if this is really what you mean when you say this in the question. To find out if blame matters in those regimes, you need to know how severe harm caused by the accident was.
    – ohwilleke
    Commented May 22, 2023 at 22:42
  • @ohwilleke slight nitpick: can't sue, unless certain limits are breached.
    – Trish
    Commented May 23, 2023 at 8:35

2 Answers 2


In a rear-end accident the car at the back is (almost) always at fault

126 Keeping a safe distance behind vehicles

A driver must drive a sufficient distance behind a vehicle travelling in front of the driver so the driver can, if necessary, stop safely to avoid a collision with the vehicle.

That means, you should always leave enough space between you and the vehicle in front to stop safely should they undertake an emergency stop for whatever reason. As a general rule of thumb, the gap needs to be about 3 seconds (about 0.85m per km/h or 4.5 feet per mile/h). At highway speeds this is about 90m or 240 feet - very few people do this but a lot more people should.

Almost invariably in a nose-to-tail accident, the rear car was not following this rule. There have been a number of cases where a rear driver avoided liability because they could demonstrate that they were following the rule but there were other circumstances that caused the collision. A recent case in Victoria had to do with a poorly designed road layout that meant the rear driver could not see the forward car until the distance was too short to stop. There have also been cases of sun-glare, insects/spiders in the rear car, and a prolonged sneezing fit.

  • The rare cases could also be intentional "brake check". But this would likely be hard to prove without video evidence?
    – paulj
    Commented May 23, 2023 at 17:02

Would all the above scenarios result in driver of car B being found most blamable? United States, no-fault

In a no-fault auto accident state, who is responsible for the accident is not necessarily checked first. Instead, getting everybody whole again is the first step.

So, first, everybody has to file a claim with their own insurance and gets paid up to the limits. Only if the damages exceed the limits, fault actually needs to get assessed. If someone is at fault, and the costs exceed that limit, then there are methods to recoup the costs to the party that had no fault, like suing the party at fault.

In the case of someone breaking, the one bumping from behind usually has violated multiple statutes, among them keeping a safe distance, driving in a manner that allows them to break safely, or anything that might make him notice too late. So unless the front car did some really weird shit, usually the fault will be found with the back car.

However, there's more going on: the insurance will try to prove that one of the insured drivers was negligent, so they don't need to pay for the negligent party. For the bumping from behind, usually, the back car can be found having driven negligently, and actually the claim "he suddenly stopped" can lead to "then you negligently drove too close".

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