[apigalore]

I had an accident exactly like that. Car in front of me fully stopped all of a sudden as I was accelerating. This was right passed the lights. No traffic or anything in front him. I don't know why he stopped. My insurance told me he was 100% at fault.

[ArteEtMarte]

Here in the UK, that happened to me on a roundabout. Elderly driver in front pulled out and then, for no visible reason, slammed on the brakes. I ran into the back of her.

It was deemed to be be 100% my fault. Here, if you run into the back of the car in front, it is always your fault. No exceptions.

It makes sense: you should always leave enough room to stop, so I couldn't really complain. But, if everybody did that on that particular busy roundabout, it would result in gridlock.

[Dzugaru]

I've heard a story from a friend that was in an accident like that. A police officer who did the paperwork smiled and said "It's the most common type of accident - people just stop paying attention to the car in front that started moving, and develop sort of a blind spot to that".

I drive for several years, and can say my brain relies heavily on this sort of predictable stuff like "that car has free intersection in front of it, it will move forward".

[sniglom]

>It makes sense

If you think like a good citizen, yes.

In a country north of UK the law was once the same. People with worn down cars would find the perfect opportunity to slam their brakes, intentionally get hit from behind and claim insurance.