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I don't know what the rules are in the US but here in Switzerland, the following driver is always assumed to be at fault. You're meant to maintain sufficient distance to safely stop your vehicle no matter what happens in front of you. If you hit the car in front of you, it generally means you didn't have sufficient distance, weren't paying sufficient attention to the road or weren't in a suitable state to be driving a car.

That's not to say that drivers here are absolutely perfect by any means; just that the expectation is that you always keep sufficient stopping distance.

It's drilled into you during the mandatory training courses that this means stopping distance as well, not just braking distance. You're also required to undertake a course that includes emergency stops in adverse conditions, like simulated ice.

> I check my mirror to see if I'm likely to get hit from behind if I brake hard.

I do this too. In fact, if I need to brake suddenly, I initially over-brake. I then check the rear-view while easing off slightly.

By over-braking I have some extra room to coast forward if the following car is still approaching too quickly. And my hope is that the initial more rapid deceleration causes the person behind to react more quickly and strongly than otherwise.

It also hedges for me in the event that I misjudged the severity or if the person in front brakes increasingly aggressively. By going harder early I can always ease off if it’s unwarranted. But in the event the car in front hits something or otherwise slams to a halt, I’ll be better off than if I initially braked more conservatively.

If you hit someone then you are at fault. Very few scenarios where this isn’t true such as is someone cuts you off and brake checks you and you manage to catch it on video and can prove it. Otherwise if you can’t stop in time if the car in front comes to an instantaneous stop you were too close and are at fault. None of the what if they have Brembos brakes matters if you can’t stop in time of an instantaneous hard stop you are at fault. At required safe distances the car in front can hit a brick wall and you should have time to stop. There is no complication here.

> and then vehicle B hits vehicle A from behind. Some people think that the following vehicle is always at fault, but this isn't strictly true (IAAL).

How not strictly true is it? My understanding in California is that unless you can demonstrate intent to cause a collision you'll be found at fault for rear-ending someone, which is pretty close to "strictly true."

If the lead car hit the brakes for no reason, he has been negligent and would be liable. This could happen if you hit the wrong pedal, or presumably if your AEB system malfunctioned and thought it saw someone in the road. It might also apply if a squirrel ran into the road and you mashed the brakes to give it time to scamper away. Most people would say it is negligent to create a substantial risk of human bodily injury to avoid the possible/likely death of a squirrel.

> Some people think that the following vehicle is always at fault, but this isn't strictly true (IAAL).

I'm having a really hard time coming up with a scenario in which a following vehicle rear-ending another vehicle isn't going to be considered to be at fault.

All of the driver's ed materials I have ever seen always emphasize that you need to be in control of your car and able to stop in time irrespective of what the car in front of you does. This includes things like a sudden stop or a sudden lane change exposing a stopped car.

Back in reality, nobody ever puts enough distance between cars, so we wind up with dozen+ car pileups.

The only scenario I can think of is the "swoop and stoop", which is what insurance fraudsters do to induce a rear-end collision. A car from a neighboring lane suddenly changes lanes in front of you while also slamming on the brakes.

> This includes things like a ... sudden lane change exposing a stopped car.

Oooh, this one has almost gotten me a couple of times. I'm much more defensive now, and when I see a car ahead changing lanes, I assume they're dodging a block wall with orphans sitting on top.

Basically, leave enough distance in front of you so even if the car you're following magically freezes in place, you have enough time to react, and still enough time after reaction to actually stop. In the real world this can be difficult to maintain. The amount of space will invite interlopers. In those situations, follow a car that you can see past, and look at more than just the car you're following.

IANAL, but you are never allowed to intentionally cause a collision; if you slam on your breaks when someone is tailgating you, with the intent of causing them to hit you, my understanding is that it's your fault.

I'm not sure why you are getting downvoted since you are essentially correct under the laws of most jurisdictions.

I only see two things in your comment that might be nit-pickable, and neither of them should be sufficient to justify a downvote.

(1) Saying "it's your fault" might be seen be some as implying that the person who slams on their brakes is the only one at fault. Most likely both drivers would be at fault.

The tailgater for following too close, and the brake checker for brake checking.

(2) You spelled "brake" "break".

You should be following cars at a distance that you can react to them slamming on their brakes. Always. Unless the car drives in reverse and hits you the following vehicle is at fault.

Should this factor in the braking ability of the car in front of me? That is, should I give more follow distance when behind a 911 versus an Escalade? I think most people don't have a sense for how quickly different types of vehicles can stop if the driver slammed on the brakes.

No. As mentioned downthread, you've got to be able to stop in time in case the lead vehicle leaves the lane and there's a stopped car or something else you shouldn't hit there. Or in case the lead vehicle hits an object you couldn't see and stops faster than their brakes would have.

At least, that's the goal. It might be that much distance is impossible to keep while maintaining flow of traffic speeds, in which case, it's a shared risk and part of why you have insurance is sometimes you're legally at fault for something you were compelled to do by forces legally unaccountable.

Law aside, you should be driving as though the car in front of you is a brick wall. That is to say, whatever the distance is between you and them it should be greater than the stopping distance of your car to a dead stop at your current speed.

If you drive this way in many parts of CA (especially LA), you will be cut off by a never-ending stream of vehicles. All of this lane-changing, happening right in front of you, will put you at more risk of collision than simply following at the distance that most cars do.

EDIT: I’m curious if this is downvoted by people who have driven in LA and disagree, or people who speculate that this isn’t the case.

"Everyone else is doing [insert patently dangerous thing], therefore I must also do it as well!"

or

"You haven't ever done [insert verb] in [insert geographical placename], therefore your concepts are invalid no matter how much [verbing] you've done elsewhere."

If it is "patently dangerous" to drive as though it is not the case that "the car in front of you is a brick wall" and that "the distance ... between you and them ...should be greater than the stopping distance of your car to a dead stop", then pretty much every driver I have ever seen in my entire life drives in a patently dangerous way. When perception time is included, this is 5.5 - 6.5 seconds, per a quick web search.

Yes, it is dangerous and it’s why most rear-end collisions happen. Fortunately if you’re not going very fast it usually doesn’t result in any serious injury.

Yes, most drivers do drive dangerously. Most will get away with it unscathed through luck, but not all. Increase your odds by driving safely even if everyone else isn’t.

The thing is, liability (and all negligence) is based on a 'reasonable person standard'. That means that if the jury is comprised of other people who drive in the same way, which you deem dangerous, then they will be adjudicated to be not legally responsible.

Also, as I mentioned above, leaving much larger follow distance than other drivers is, in places like LA, not a way to strictly enhance anyone's safety. Even if you leave a normal-ish amount of follow distance, you'll get cut off from time to time. If you leave 6 seconds of follow distance, you will be cut off all the time, which is dangerous for you and for the other drivers.

> Certainly it would not be the case in the event of the lead car braking erroneously.

Not certain how you are rationalizing that.

If I think i see a deer jump out of the woods and hit the brakes then

a) I didn't need to brake, but my understanding of the world said I did, safety first!!

b) the car behind me would still be at fault.

Self driving vehicles would be the same. They could easily see something that a driver wouldn't and thus hit the brakes and stop a collision, but the human driver behind it wouldn't' see the obstacle and therefor think the autonomous car was breaking erroneously.

According to my defensive driving course, minimum 4 second follow distance and 1 additional second for additional factors such as towing, tiredness, night/rainy conditions, and several others.

I think it was NSC who did the certification. https://www.nsc.org/safety-training/defensive-driving

What does IAAL stand for? Is it “I Am A Lawyer”? If so, this strikes me as a _really_ fascinating take

There's a problem with driving like this.

The whole time that a driver is checking their mirror(s) to look behind them, attempting to ward off a crash that they cannot actually control, and that may not even have the potential to happen, they're NOT slowing down for the real observed conditions ahead of them that DO warrant slowing down or stopping for and that they can control.

I mean: Suppose a driver is going down the road at 25MPH and sees a kid run into the street chasing a ball, necessitating a hard stop.

Which of the following should the driver do?

  A) Stop.  Hard.  Now.  Remove as much kinetic energy from the problem as possible, as soon as possible.
  B) Sound the horn and proceed through the kid; the kid should know better and Darwinism is more important than anything else.
  C) Look around, check mirrors, and spend some time (while still travelling at 25MPH) attempting to triage whether it is better to hit the kid, run off the side of road, switch to F1 mode and neatly drive around all moving obstacles, stop hard, or do something else?

The only correct answer here is A. It is the driver's job to avoid running into people, and to stay on the road, and to remain in control of their own vehicle, and braking sooner is more effective at accomplishing this than braking later is.

(This applies to the drivers of any cars that may be seen in the rearview mirror, too: It's their job to avoid hitting the car in front of them even if it is suddenly stopping, and to never follow so closely that this would ever be a problem for them to begin with.)

Usually you can do things in this order:

a) brake hard b) observe forward and rearward c) modulate brake application as appropriate d) go to b

Sometimes you might add steering inputs. Depends on the situation. It doesn't take long to go from 25 mph to 0 mph though, so you may not have time to loop.

> The whole time that a driver is checking their mirror(s) to look behind them, attempting to ward off a crash that they cannot actually control

I didn't suggest that someone drive around with their eyes on their mirror the whole time. I only pointed out that before hard braking, I will check my mirror at the same time. If a kid ran into the street, I'd brake hard regardless since the consequence of a forward collision is terrible.

You'll notice the scenario I described above, which is much more common than kids running into the street, is a light turning yellow. Your hypo with stylized answer choices is one that anyone would pass with flying colors, and it's disingenuous to suggest that someone posing my question would "look around, check mirrors, and spend some time attempting to triage".

If someone poses a common dilemma with a balancing of harms, it's facile to respond with a clear-cut hypo and then make it sound like the person wouldn't know what to do in that circumstance.

The decision of whether to proceed through a yellow light or whether to stop also has nothing to do with whatever may or may not be seen in the rearview mirror.

I mean:

A driver is approaching an intersection with a yellow light, indicating that it is about to change state.

Should the driver:

  A)  Look where they're going
  B)  Look somewhere else entirely

Sure, if you approach an intersection with a yellow light, you should stop.

However, the situation is you approach an intersection with a green light, and then it turns yellow.

You should stop, if you have enough room to stop and it is safe to do so. If the vehicle behind you is unlikely to stop, it is not safe to stop. You can't tell if the vehicle behind you is likely to stop by looking ahead of you.

At the same time, I'm assuming it's safe to proceed through the intersection given the light was recently green. If it's not safe to proceed, you should not proceed regardless of the light.

Driving with other road users is all about considering the likely actions of other road users, observing and reacting. Sometimes that means you need to look in multiple directions.

Our traffic rules are set by laws.

There is no law requiring a driver to check their mirrors before stopping for a traffic signal.

Meanwhile: There are many, many laws requiring a driver to not run into the car that is in front of them, and requiring them to avoid doing things like tailgating that increase the risk of this happening.

> There is no law requiring a driver to check their mirrors before stopping for a traffic signal.

There are plenty of things that are not required by law that are nonetheless a good idea. Also, no one (other than you) ever said anything about checking multiple "mirrors". I referred to checking your mirror (singular), which was a reference to the windshield-mounted rear view mirror. There would be no reason to check the side view mirrors, which wouldn't tell me anything about whether it's safe to stop.

Who said anything about looking somewhere else entirely? My rear-view mirror is in right in front of my windshield. Also, I've been looking straight forward for the last while so I know what's there. It's also unlikely that it's not clear in front of me, since the light has been green. Checking to see what's going on behind me is to make sure I'm not going to be rear-ended (and has saved me from being hit at least a few times in the last decade). Would I have been in the right to hit the brakes, oblivious to my surroundings? Perhaps. But I still would have been hit, and my kids might have been mortally injured in the back seat. So yeah, I'll keep checking my mirror when a stale green turns yellow as I'm approaching.

If you can actually see both views at once (things in the mirror, and things ahead), then why aren't you looking at both of them concurrently all of the time? Why ever deviate your gaze?

I can take in the scene in front of me with my parafoveal and peripheral vision while looking at the mirror with my foveal vision. It doesn't work the other way around, as anyone who has ever driven would know.

That's like asking why I can't read a book while gazing ahead as I'm walking, since I can easily do the reverse (walk while gazing down at a book). Seems like you're just here to stir things up, so I'll leave you alone with your thoughts!

Carry on, then, dear sir: Clearly, this is all sorted for you, including the tailgating you defend in LA.

Best wishes. Try not to kill anyone.