GPS Used As Defence In Radar Speeding Case 464
James Thigpen writes "There is an article over at Ars Technica about an accused speeder contesting his speeding ticket based on his car's built-in GPS system's records. According to the article his car says he was going slower than the radar gun clocked him at. Contesting a ticket based on GPS data has never before been tested in court."
Video Evidence (Score:5, Interesting)
Plus it would be cool to have onboard footage of your driving for analysis and review.
Re:Video Evidence (Score:5, Insightful)
Re:Video Evidence (Score:5, Interesting)
In my opinion, if they're not enforcing speed limits in the few areas where they are actually beneficial, then we should abolish that system entirely as it is working for no one. I pay taxes like (most) everyone else, if that money isn't enough to afford proper police without the need for profiteering practices, then raise my goddamned taxes and destroy those stupid radar guns. Maybe then people will start respecting these so-called peace keepers again.
Something is very very wrong with the world when honest law-abiding citizens live in fear and/or contempt of the law.
Re:Video Evidence (Score:4, Interesting)
Imho the latter outweighs the former and radar guns are generally a good thing.
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Speed limits are arbitrary, and (specifically on the highways between Brisbane and Melbourne) designed to make money, not save lives.
Re:Video Evidence (Score:5, Funny)
There's a simple solution to that - if you don't exceed the speed limit, they won't make any money from the cameras. So, if they are about making money, then they would be removed once they stopped being profitable. Unfortunately, it seems highly unlikely to get the majority of people to obey the road rules for even one day or one week - so it looks like the cameras are here to stay. I still think it would be a hilarous protest, though - everybody obey the law today, and screw the police and government. It would be an act of civil obedience.
Re:Video Evidence (Score:5, Interesting)
I don't think so.
Kind of right. What they actually do is reduce the tolerance levels. This happened in Victoria (Australian state - probably has some of the most brutally enforced speeding laws *in the world* - unsurprisingly its roads aren't meaningfully safer), where you will be booked for driving as little as 3km/h over the posted limit (how this lines up with speedometers only having to be accurate within 10% hasn't been tested in court yet AFAIK).
So whereas you use to be able to do 120km/h in a 110 zone without too much to worry about, now you'll get pinged for 114km/h. No-one without an agenda seriously thinks a ~3.6% speed differential has any meaningful impact on road safety.
Police and politicians have to get places by car, too.
Poor examples. Police can (and do) break the speed limit at will with little fear of either detection or punishment. Politicians are typically being driven, for short distances, and only in urban traffic.
Generally I think the speed limits are pretty reasonable. It's just that drivers can't stand any form of restriction, and always want to go faster.
Also untrue. Research has demonstrated that in typical conditions - especially high speed roads like motorways - drivers choose the safest speed for the conditions. People actually interested in road safety know this as the 85th percentile. It's what the posted limit on a road *should* be set at for "maximum safety" (but usually isn't).
For a concrete example, there is a major highway north of Brisbane, Queensland (2 lanes each way, divided, limited access). Some years ago the speed limit was *raised* from 100 to 110km/h (amidst the typical outcries from ignorant fools about how the roads would be awash with blood). Not only does the road remain as safe as it was, but average traffic speed actually *dropped* by about 3km/h.
Seriously, if people can't follow a simple speed limit, why should they be entrusted with more liberty on the road? If people would obey them and drive like sane people, then they could be allowed to drive faster. You have to earn responsibility.
Because following a badly set speed limit - *especially* on higher speed roads like motorways - actually *increases* risk. *DRIVERS* have to earn trust ? What a joke. Maybe if the government was more interested in saving lives than making money - and demonstrated it - we'd be able to trust them with things like speed limits.
Very, *very* few governments have shown any real interest in improving road safety. Why would they ? Doing so would be expensive (both in monetary and political terms) and it's trivial (and cheap) with a good advertising campaign to demonise things like speeding (despite it being a relatively insignificant factor in overall road safety) so they have someone to pin all the "carnage" on.
Re:Video Evidence (Score:4, Informative)
Yes, speed limits are often arbitrary and designed to trap drivers. But claiming that speed limits are never related to safety is foolish, and claiming that speeding is not at all dangerous is also foolish. Higher speed increases both your reaction distance and the severity of any mistakes. Increasing either of these reduces safety.
I'm glad I don't have to share the road with you.
Re:Video Evidence (Score:5, Insightful)
Actually, some college students at Georgia State University tried an experiment [google.com] in which they blocked off all lanes on Interstate 285 going 55 miles per hour, the speed limit. Keep in mind that most people drive 65 to 70 on that road.
As a result, the people behind them got very angry and began active extremely dangerously. One van even had an accident when he passed them on the right shoulder and clipped a car that was parked in the emergency lane.
There is nothing inherently dangerous about going faster than the speed limit. Sometimes, when it's raining and there is low visibility, driving the speed limit is unsafe. Other times, when there is low traffic volume, high visibility, and the roads are dry, it's perfectly safe to go 10 to 15 miles per hour above the limit. The law doesn't take that into account, though, and as a result, the speed limit is set arbitrarily low on almost every road.
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In Europe, none of what's described in the article would be happening because you have no right to contest a ticket over there (except maybe in England since their legal system and ours have a common basis, but maybe not even there).
In the UK you can most definitely contest a speeding ticket [bbc.co.uk]. In fact you can in France [sudouest.com] and Spain [spainlawyer.com] too. What makes you think the legal systems in Europe are so unjust?
(Note that the Spanish link mentions fees of €930. You don't have to pay that to contest a ticket, that's just what some lawyer wants to charge for assisting you... seems lawyers are the same the world over ;-)
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Yikes. Who told you nonsense like that ?
Of course you can contest your speeding tickets over here. Heck, the appropriate advice is printed on the ticket you get by mail. However, since we've got a "loser pays" court system over here, you'd better be ready to cough up the court costs in addition to your fine when you lose. Also, police here are quite good at
Re:Video Evidence (Score:4, Insightful)
Comment removed (Score:5, Insightful)
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Probably depends on whether you're in a one- or two-party state; in the latter case, everyone being recorded has to consent.
Is there by any chance an exemption saying the cops are perfectly free to record you without your consent?
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The video and data can be used against you as well, they might demand more data than is actually pertinent to the case and nail you for something else instead.
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> This button should also be linked to the air bag triggering mechanism for the same effect.
Given a suitably-cheap "cellphone-modem-on-a-PCMCIA-card" device, a headless laptop, and a shell script, the button chould also upload the contents of the buffer (or all five buffers, one per camera) to YouTube.
Your friends/family, who have an RSS feed configured to freak out should
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Re:Video Evidence (Score:5, Insightful)
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Like I say though, IANAL. Or AA.
This could only be the first step (Score:3, Interesting)
Re:This could only be the first step (Score:4, Insightful)
Re:This could only be the first step (Score:4, Informative)
GPS with PGP (Score:2)
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This is an old story by the way. I can't remember when I first read it but it must have been months ago.
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See, the real problem here is that the people on this site are just to tech savvy. Could you imagine a judge listening to your defense and watching you present GPS data, then sayings "The data you are presenting is not a secure data set and could easily be forged. We therefore cannot accept it as adequate defense. Do you have anything else to say?"
Of course I couldn't see this happening but it would be a riot.
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What I don't understand is how this kid is explaining the discrepancy between his GPS and the radar gun? The radar says he was going 62, but he claims he was going 45? How would that happen? That's a big difference when you consider the accuracy of radar guns. I'm not saying the
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My Garmin recently reported my max speed as 142 mph. While conceivable that I could hit that in an auto, it's highly doubtful on my loaded touring bike.
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There are two big problems with this case:
1 Malone's parents had the GPS system installed in order to track the whereabouts and speed of their son, whom they readily admit has a lead foot. In fact, he has already been grounded for having gone over 70 MPH after the GPS was installed.
2 The debate is likely to come down to how often the GPS device calculated and reported ground speed. Petaluma police lieutenant John Edwards told
Re:This could only be the first step (Score:5, Funny)
Yup. On most people's home projects list that's the one right after "Get microwave to stop blinking 12:00."
Open source GPS? (Score:5, Interesting)
Breathalyzer Source Code Revealed [slashdot.org]
Closed Source -> Charges Dismissed? [slashdot.org]
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Can't be that accurate if even after calibration they are suspect.
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Well, it wouldn't be the police who would request the source to check for accuracy, it would be the prosecutors--and that's not a path they would want to go down. They've been fighting it tooth and nail in regards to the breathalysers, and using it against GPS devices would create precedence forcing them to defend the source on every tool police use for traffic enforcement.
used in Taiwan (Score:5, Informative)
Brings accuracy into question (Score:5, Insightful)
lets say that the gun is wrong 1% of the time, which in the case of a cop handing out tickets by hand is okay (imho) because there is human intervention, he (or she) can look at the thing, bang it on his hand a little, and shake the error off as a fluke.
The speed cameras on the 101 in scottsdale, arizona issue about 250 tickets daily. Thats 2.5 tickets daily that the gun gets wrong (the 1% figure was pulled from my ass, but I'm using it as an example). With THIS there is no human intervention at all (other than a pissed off commuter)..
grr...not sure where i'm going with this, I just REALLY hate it that humans are being taken out of (at least that little part) of the legal system. I don't want my fate decided by a computer!
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qkihatethelamenessfilteritsasannoyingashumansxu
Re:Certainly does (Score:4, Insightful)
They use induction loops buried below the road, and work exactly the same way you do - compare times at positions A and B.
Radar and GPS were in check in California (Score:3, Informative)
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if he stopped for a light, then put his foot down you could concievably be doing 60 whilst recording an average of a lot less. So both readings can be right, its just one is an instantanous speed, the other an average.
Where did you get the idea that GPS systems report average speed? They read your location, then calculate the speed based on the distance covered and the time elapsed since the last read. The elapsed time between NMEA data transmissions from the GPS unit is (by NMEA standard) one second. Subsequently, the vast majority of GPS devices update at 1Hz. Readings previous to the most recent two are not used in speed calculation. Because of this, there is simply no way a speed variation of 17MPH could be "lost in
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Testing in UK court case and GPS won (Score:2, Informative)
http://news.bbc.co.uk/1/hi/england/wear/7033353.stm [bbc.co.uk]
Are you serious? (Score:3, Informative)
Speed = Distance / Time (Score:5, Informative)
Re:Speed = Distance / Time (Score:5, Informative)
1. What is the time the GPS device averages over? On the devices I've seen it updates about every second. Unless you have a REALLY nice car you're not going to go from 65 to 90 and back down for long enough to average 65 over that kind of time.
2. At least one state (MA) and perhaps others have laws that require your AVERAGE speed over some distance (I believe MA is 1/4 mi) to be over the limit for a speeding ticket.
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They have traffic laws in Massachusetts? When did that happen?
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Minor point, but you'd have to go from 40 to 90 in one second then back to 40 the next second to average 65, so you'd need an even nicer car.
many units clock max speed (Score:3, Insightful)
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First, when the GPS unit itself calculates the speed, it records your instantaneous velocity, not an average. It calculates this using the doppler shift present in the GPS signals picked up by the unit, not from how far the unit has travelled.
Second, even the cheapest GPS units I've seen update at least once per second.
Third, the delay, or time offsets of the arrivals of signals from the GPS sattelites are exactly how a GPS unit calculates it's velocity and position. Once a GPS reciever has got a "lock" o
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Re:Speed = Distance / Time (Score:4, Informative)
Let's go over some basics:
a) There is no such thing as "instantaneous velocity" - as velocity is a function of time.
Corrolary: You can
And the problem with the radar/lasar guns is indeed that, because they try calculate "near-instantaneous velocity" they are very *very* susceptible to error, particularly at the ranges the police often try use them at (hundreds of metres).
b) Noticing a doppler shift in waves from a (relatively) stationary source would require that you have a non-zero velocity relative to the source (ie the distance between you and the source change). I'm reasonably sure this velocity would be immeasurable from a consumer car in a GPS over a short period of time and, further, that any measurable doppler would be due far more to the
I.e. I havn't done the calculations (it's not just linear, cause any doppler will be induced by the curvature of the earth, not directly by the car's speed), but you're talking about measuring doppler due to
So I call bullshit, unless you show me the numbers to prove otherwise.
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Ah, that's roughly about 1mm for 35m of forward movement btw. For reference, 35ms-1 is about 126km/h (78mph).
Instantaneous velocity (Score:5, Insightful)
You see, Instantaneous velocity is the limit of the average velocity where the time of averaging tends to zero.
In other words, the value of f'(t0), where the position x is x = f(t) at a given time t0.
Or in other words, angle of the tangent of the curve x = f(t) in the given time t0.
Now, if your argument is that "a GPS device cannot give the measure of the instantaneous velocity because it does not sample fast enough to get a really good approximation of the curve x = f(t) and hence, the value of f'(t0)", then you could be right because 1Hz is not really a high sampling rate. But you could have said so
The (analog) speedometer in most cars measure speed by measuring the RPMS of the gear box and multiplying by gear ratios and tire size: they normally do that with a continuous measuring (springs and coils), and what they measure is a good approximation of the instantaneous velocity of the vehicle. A good analog speedometer is somewhat reliable, especially if the scale is correct(*)
(*) their scale is not linear like you see in a normal car: but exponential, so it should be like: and this is why they have a "sweet calibration spot" (normally near the top of the dial; have you already thought about why they make 1.2l-engine cars with 220 km/h marking in the speedometer [a speed they usually don't achieve even in freefall
DISCLAIMER: I was a software developer for a road engineering company for one and a half year.
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Don't be so sure.
Instantaneous velocity is the limit of the average velocity where the time of averaging tends to zero.
Yes, that's obvious. You'll note my original post mentions "You can
You're unfortunately missing the words "approximated by", in between "is" and "the limit". Interestingly, given your po
Sorry but you are wrong (Score:4, Informative)
The time between samples is what's important here. If it's only a few seconds then there's a good case for innocence. If on the other hand it's 30 seconds or a minute, the cop with the radar gun wins. BTW, it is the radar gun that uses doppler to measure speed.
--
This space for rent
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It depends on too much (Score:2)
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It makes it trivial to get out of speeding tickets in MA, but for some reason people don't seem to know that.
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From my understanding, and the contention of the officer, the GPS logs average speed.
Your understanding and the contention of the officer are correct, but misleading. It's based on a failure to understand how short an interval that average is. GPS units report speed at one second intervals, which is how often the NMEA standard interface updates. Therefore, the speed reading they give is the average speed for that one second interval. This is not meaningful in the context of a 17MPH discrepancy, though, as it's highly doubtful that one could have a large enough swing in velocity over one se
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From my understanding, and the contention of the officer, the GPS logs average speed. Which means that during a short period of time, the defendant could have greatly exceeded the speed limit (and was clocked by the officer at that time), while the average speed was far lower than that. In which case, both the cop and the defendant are correct, and the cop is till valid in giving the ticket...
and
The debate is likely to come down to how often the GPS device calculated and reported ground speed. Petaluma police lieutenant John Edwards told the AP that since GPS is satellite-based, there's a delay involved, and that Malone may have sped up and slowed down in the window between measurements, which could be as long as 60 seconds.
Yes, it comes down to accuracy. But Lieutenant Edwards is wrong about the technology. The GPS satellites do not record the cars movements, so the lag time between the satellite and the car wouldn't matter. The only thing that matters is how often the car's device is recording speed, which could be up to once every second or maybe even more frequently based on the GPS technology alone. Really, what matters here are the technical specifications of the recording device and what data it recorded.
If it
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if you get pedantic about it, and i'm hoping other with more physics-fu can enlighten me here, how exactly does one measure the precise position of a moving object relative to time? (you'd obviously nee
What's to prevent me from doctoring the GPS log? (Score:4, Insightful)
I have used this (Score:5, Interesting)
In San Antonio, TX I was pulled over for doing 76 in a 75 zone. I successfully argued that the GPS was more accurate than the RADAR, when I said that it used "government satellite signals."
In fact, most police radar units are +/- 3mph. A consumer GPS speed indicator is typically accurate to within
When working in ship navigation systems (Laser Plot), I was involved in dumping track information from a ship to show that it was not in an area when a boating accident occurred.
The hacking issue is correct, one can always hack the data. The Cop can lie about the reading on the radar unit too. If it gets to 'real court' you have the standard issues of scientific reliability (Daubert test) and the authenticity of the data. In the late 90s, there was a case (in Georgia, I think) where a speeding conviction was thrown out because there was no reliability of the laser speed testing introduced.
Re:I have used this (Score:5, Funny)
For what, Driving While Black?
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Assuming that this is not a typo, I am tempted to call BS on this for several reasons.
Until the repeal of the 55/65 national speed limit, all freeways in the San Antonio area were 55 mph or less, and I-35 was 55 mph all the way to north of New Braunfels. Most freeways inside of Loop 410 have now gone to 60 mph. Outside of 410, speed limits are generally 65 on the Northside and 70 on the Southside. Speed limits jump up to 70 outside of Loop
You are right. (Score:2)
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I'm sure that a dedicated GPS device can devote a lot more chip-space to getting accurate signals though than a phone that does everything.
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Bah. (Score:4, Funny)
So should I get some sort of prize for my Highlander that can go 352 MPH, based on my Garmin 350 "trip max" history?
I personally don't remember driving 352 MPH, even when driving up I15 to Vegas, but then again, maybe my wife did it when I wasn't in the car with her... yeah that must be it.
Speeding cases are easy to win (Score:4, Insightful)
The cops have to prove their case. This means showing up to court with the proper evidence. The evidence has to be maintained and presented in a condition where it is admissible. Very often, one or more of these things do not happen and the defense wins by default.
Everyone should always take their speeding tickets to court. Speed limit laws need to be made unprofitable for the government and then maybe we can get our freedom back on the roads.
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I've also been convicted on obviously inadequate or downright forged evidence, as when a cop pulled me over for running a red light and illegal
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Speeding cases are different than yours because there's a measurement involved. Even when the cop shows up, he can't say "I saw him going faster than XX speed". No one can be assumed to have the ability to reliably judge speed by sight, and it's easy to demonstrate that. Measurements are only as accurate as a measuring device. The cop has to prove that the radar gun was accurate. These are all hurdles that the cops have to overcome. They fail often.
If I were the judge. . . (Score:2)
VORAD units have been used this way (Score:5, Informative)
Eaton VORAD units, which are a phased-array anti-collision radar for trucks, have been used to provide evidence in favor of the truck driver. [etrucker.com] The VORAD units track individual car-sized targets, and provide range, range rate, and azimuth. Range and range rate are quite good; azimuth isn't that accurate. The control unit keeps track of recent events ten minutes before a collision, and also has speed info available. The latest versions can interface with GPS and other vehicle systems. This allows detailed accident reconstruction.
It's most useful where an accident resulted when someone drove in front of a truck. [etrucker.com] The VORAD record shows not just what the VORAD-equipped vehicle was doing, but what the other vehicles were doing.
Actually, I know 2 ppl who have contested; lost (Score:3, Informative)
Your Mileage May Vary (Score:5, Informative)
In most jurisdictions, such traffic cases are considered civil and the standards for evidence are different than those of criminal cases or what you may see on 'Law & Order'. The judge is free to weight the officers evidence more highly than yours and presume it to be correct unless you can show overwhelmingly that it is not. Sort of like being guilty until proven innocent.
Furthermore, courts have quite a bit of latitude to allow or deny the admissibility of data as evidence. For example: Radar is quite accurate (it reads the speed of an object quite close to its actual speed) but not very selective (it might be reading the speed of something else, or interpret some RF noise as speed). Take the boilerplate testimony that an officer reads about 'calibrating the gun with a tuning fork' and all the b.s. about standards traceability. None of this is necessary, as the most common source of errors are due to poor selectivity. But it sure sounds great in court.
In fact, calibrating a radar gun with a tuning fork is a good demonstration of its susceptibility to AM noise. An ideal radar gun should only measure frequency shift due to the Doppler effect and reject the sort of modulation that a tuning fork creates. After all, the instantaneous velocity of its tines is dependant on its amplitude and the average velocity is zero (unless you throw it). But no court would hear such an argument, as it would undermine their entire traffic enforcement/revenue collection program. And, as a civil case, they are not required to consider it.
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Its semantics, but I'll admit that you are correct. The officer verifies the unit's calibration.
SMD vs GPS (Score:4, Informative)
Like it or not, the radar gun is a more accurate speed measuring device than a GPS.
UK Stuff (Score:3, Informative)
In the UK the speed camers are checked by hand (or at least are ment to). They do this by taking 2 photos from the camera at a set time interval. On the road by the camera there is meant to be a lot of little white marks which are big enough to see in the camera and are spaced at
Though i know this system is sometimes ignored by police int he uk
Also in the UK (at least n.ireland) the police are meant to run a test car though speed traps a few times documenting it and keeping a tape etc.. If they fail to produce a copy of the documentation on this to you at the scene if you ask for it then they dont have a case if oyu push it to court.
Another thought about safty on the road is around where i live they have started putting in speed bumps everywhere. Which is meant to slow the traffic down to improve safty. Slow it donw it does. It also annoys the crap out of people driving over bumps all the time and it makes the safty problem worse. Since all the traffic is now slower no gaps form in it so people can no longer cross the road when its busy whichout taking higher risks which is exactly the opposite they were traying to prevent.
Its amazing what the UK goverment can come up with.
Not Going To Work (Score:5, Informative)
Simply put: This is not going to work.
The system is rigged against fighting speeding tickets. Even if you've got the money to pay for evidence collection, expert witnesses, and everything else -- BEFORE your trial -- you'll still lose. The justice system will protect the police from having even one ticket investigated, because it calls into question other tickets the officer may have written using the same or similar equipment; a very large expense. It just won't happen.
Here's a TRUE story, as related to me by my friend who drives commercial truck:
My friend was pulled over by a police officer for "speeding" and given a ticket for 75 in a 65. Only one small problem here: The area in Ohio where he received the ticket was absolutely flat, and his truck is GOVERNED at 68. Exceeding 68 miles per hour on a flat road is literally IMPOSSIBLE for his truck, so says the manufacturer of the engine and the manufacturer of the vehicle. Understandably, my friend was very upset at receiving such an obviously bogus ticket, and decided to fight it.
Nice thing for my friend, engines in big trucks have computers to track fuel usage, speed, etc. over time. Getting the data from the engine is a matter of taking it to the service center, hooking up a computer, and getting a printout. He obtained this printout and showed it to me; it's so simple my grandmother could easily see his truck hadn't gone over 68 at any point during the data recording. The dates were clearly marked; it showed on the day in question, the truck did not go anywhere near 75.
Armed with this and people willing to testify that the truck's governor was functional and the printout was accurate, he attempted to fight the ticket. He was informed that he would have to pay all of the trial costs up front ($10,000) before the trial began, and even if he won, he wouldn't be able to get reimbursed for this expense. So basically, it came down to a choice: Swallow pride and pay the $350 ticket, or pay $10,000 to prove he was in the right and get the ticket voided on the basis of the evidence.
Sadly, but wisely, my friend opted for the former. Proving his case was not worth the extra $9650 it would cost to do so.
Take note: Traffic court is rigged against regular people. If the highwaymen in blue try to rob you, just give up the money; losing your time, energy, and sanity over government sponsored theft will just victimize you more.
I work for the radar company... (Score:5, Interesting)
I work for the radar company that made the radar gun the cop used. I don't have all the information about what happened, but I have a hard time believing the GPS is more accurate.
Radar guns are certified regularly, which is most often a pretty simple accuracy test (but very well could have been a full diagnostic), so it's doubtful the radar gun was malfunctioning (iirc, those guns have an internal lockout in case of malfunction).
Also, remember that we're talking basically the speed of light here, with some minor latency for the unit to process the Doppler shift. Radar's pretty much instaneous, within miliseconds, at least.
Now, that's not to say that the officer didn't make an error. Radar's not an exact tool--b/c the beam is so wide, you can pick up a lot of things and an untrained officer can get some misleading speeds.
At the same time, remember that most traffic officers do this all day, at least five days a week. They make mistakes just like anybody else, but they're rare. And for that matter, officers are trained to use the radar as a confirmation of their own judgement of how fast the vehicle's moving. And since they're doing it all day long every day, they can tell you within a mph or two how fast a car is going just by looking at it.
Again, I'm not pretending to have all the information, but if it came down to trusting GPS or trusting the radar, I'd trust the radar. It's just a simpler tool, with less hoops to jump through (and fewer things to go wrong).
Disclaimer: I'm in marketing for Decatur Electronics [decaturradar.com]. But for what it's worth, I use Linux on my machine at home, hehehe.
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Re:First Post? (Score:5, Insightful)
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chain of custody is important for proving guilt (beyond a reasonable doubt). Exculpatory evidence doesn't need such high standards (it just needs to give a judge or jury doubt).
At least in theory. Traffic court judges exist mainly to uphold a cop's decision.
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Ive seen them run that fast when their hair is on fire.
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