IANAL but this seems wrong to me. The sonographer provided testimony in the jury room without going through the process of being qualified as an expert witness or cross-examined. He should not have done that, whether or not he was correct. And two previous posters here have suggested how he might be incorrect.
Since there are a plethora of speeding ticket stories in this thread, I’d thought I’d offer a quick glimpse behind the curtain.
When I began my prosecution career, I started, as most do, in traffic court in a smallish county. A majority of the tickets that went to trial were speeding tickets, which people think they can beat. A couple of the magistrates I was in front of had what they referred to as the “interesting theory” dismissal where, if a defendant on a non-accident speeding ticket showed up, wasn’t a jerk, didn’t have a horrible driving record and presented a defense that involved physics, higher math, or another “interesting theories” the magistrate would dismiss the ticket. Talking with them after court, they seemed to think if someone went through all the trouble of preparing a defense, they might as well acquit them. It had little or nothing to do with the actual science, but it was amusing none the less.
Since that time, I’ve used math, probabilities, and extrapolations in many cases, most notably DNA cases and DUI cases. Jurors seem to put a fair amount of credence into an expert who can make scientific arguments.
In Ontario, and at least four other states or provinces in North America that I’m aware of, running an amber light is also worth a ticket, albeit different from running a red light.
IANAL either, but recently I was interviewed as a potential juror for a vehicular manslaughter case. The lawyers and the judge all seemed quite concerned how I, as a mathematician, would evaluate the expert witness testimony that the case would involve. They said, essentially, that even if I knew that the “expert” was wrong, based on any specialized knowledge I might have, I was to accept the testimony as if it were correct (and certainly not let my fellow jurors in on the error). Ultimately, I did not make it on to that jury.
Here in the UK, an amber light means that you should stop if you can do so safely (no emergency stop etc) - if you’re too close then the correct thing to do is go through.
Years ago, I wrote a short story in which the protagonist used the Mean Value Theorem to get a traffic ticket dismissed. Looks like I wasn’t as original as I thought.
A friend of mine used that once; he got his timestamps from toll booths. If I recall correctly, an officer had wrongly accused him of speeding, and my friend basically proved that in order for him to be travelling at the speed the officer cited, he would’ve had to also park on the road for no less than 3 minutes, or something like that.
This I want to hear. The only context for the (differential) mean-value theorem that comes to mind is considering position as a function of time. In this case, all the theorem says is that there exists a time where you were going a certain speed (as specified by the theorem).
This is ususally brought up as an idea for proving speeding violations for, say, travellers on a turnpike where the distance between booths is known in advance and making time measurements on a stamped ticket can sometimes establish that at some point the driver was speeding. I don’t see how it can be used to get a ticket dismissed though. Along a linear path you could only manage to invoke this theorem to prove you weren’t speeding if you could somehow bound your speed from below. I don’t think you could do it at all if there’s any possibility of looping back on your own path.
So, did your character prove he never went below a certain speed along a linear path? Is there another context in which you invoke the theorem? Were you just confused about what the theorem actually says?
Right, I didn’t say it was a speeding ticket. In the story, it was a ticket for running a stop sign when the guy had rolled up on a hill, rolled back a few inches (it was a manual transmission), then proceeded. He got the ticket because the cop didn’t think this counted as hitting a complete stop, but established in court that if he’d rolled slightly backward before proceeding, then he must have passed through the same point twice. His average speed between those two moments would have been zero, and therefore there was at least one moment at which his speed was zero. I.e., a stop.
Hey, I didn’t say it was a good story. I was about 18 or so and had just learned what the Mean Value Theorem is.
Ah. Mistaken as I may be in many jurisdictions about yellow lights, I’m sure that the laws regarding stop signs specify a “full and complete stop”, which is usually defined as a certain length of time at rest, rather than as a single point of time at rest.
Not to be anal, and IANAL, but if he rolled up to the sign, then rolled backward, then there was a point where his speed was, indeed, zero. Whether it be at the transition point from rolling forward to rolling backward, he hit 0 at some point in time.
I’ve never seen the length of time one must spend at a stop sign specified in any lawbooks, so it follows that 1 second could count as full and complete.
… or perhaps waited 3 minutes behind a few cars in front of him at the toll booth ;). That’s a pretty slim margin of error to argue; I’d feel safer with a 15 minute time lapse.
Plenty of people - I’ve seen it and almost done it myself. When you’re running a yellow you tend to be focused on the light and if anyone moving is going to hit you, not what the make of the stationary car sitting safely stopped across from you is. Tunnel vision comes very easily under such circumstances.
I’m guessing it depends what the law means by “full and complete.” For instance, if you came to a literally momentary stop moving forward, it’d be basically indistinguishable from rolling forward. Problem. But if I was the cop or judge, I’d OK it if you rolled backwards two inches - you should be equally able to see that nothing’s coming there as if you’d stopped for that time. We need a lawyer I think.
Well that’s my point. I’m not saying that the ticket shouldn’t have been dismissed, but that the single instant guaranteed by the mean-value theorem (and the Newtonian approximation to physics) is not sufficient to invalidate it.
Though on re-reading I see in the story the argument Jackelope first said he used was that the average speed was zero, over a back-and-forward path. Which is true, and possibly even reasonable, though I doubt the law defines it quite like that. Also, I think MVT is overkill - IVT would be enough, since he merely claimed it was at the same point twice, and most people would be more amenable to that claim if you didn’t invoke eithe VT. But I could see it being a plausible loophole, depending on how the law was worded - I keep forgetting this was fiction.
The claim about average speed between two points is the precondition for invoking the MVT. Since the average speed is zero, there must be a point in between where the actual speed is zero. I’m not sure how the Intermediate-Value theorem would apply any more directly than the MVT, though. In fact, he did implicitly invoke it to show that he passed through the same point again after rolling back a bit.