You got off because the Radar gun didn't have a certificate of Calibration less than 6 months old. Plain and simple. In almost every state radar guns must be operated according to the manufacturers directions which includes calibration every 6 months. If the Officer doesn't have an up to date calibration certificate, he has no case.
Agree with the above. I have a fair amount of experience with traffic court- you did not get off because of your GPS; it was because of the officer's answers to your questions. Good job asking, though.
The #1 tip for any court situation like this is the question the officer about events on the day it happened. By default the officer's word (and/or his radar gun) is worth more than your own, but if you can get him to say ANYTHING that calls into question his recollection of events, then his credibility is reduced. Incidentally this is also why most cops take great notes.
"He mentioned that he was not familiar enough with GPS technology to make a decision based on my evidence, but I can’t help but imagine that it was an important factor."
So the judge categorically stated that it wasn't a factor in his decision but the author imagines it was...
The difference between what you want to hear and what was actually said.
The reality is that he got lucky because he heard what the lawyer before him said and copied it and the police officer was ill prepared (possibly because he knew that the defendant was representing himself which is normally a sign that someone doesn't know what they're doing).
I assumed the judge didn't want to set a legal precedent for accepting cell phone GPS data. He entered the verdict in such a way that it couldn't be used to influence later cases.
this court may not have any lower courts, in which case you'd be right - albeit for the wrong reason.
Actually, that was precisely what I was saying. It's obvious to me that a local traffic court has no lower courts below it.
In addition, to be a precedent, the decision needs to be published (as I understand it, but IANAL). When you think about it, this must be true: no court can follow a precedent that cannot be discovered.
He might have simply meant that he didn't want to set any precedents for future rulings by himself; i.e., start handing out free passes to anyone with a smartphone.
Tyrannosaurs, you are very right that I got quite lucky taking note of the lawyer speaking before me. I also got lucky that the officer unfortunately was not prepared for traffic court with proper details about his training and calibration for his radar gun.
Flemlord, You nailed it about him not wanting to get into a bigger mess by making a decision based on GPS information. Here's a ArsTechnica article about the ongoing debate between GPS and Radar Guns - http://arstechnica.com/gadgets/news/2008/07/nabbed-for-speed...
I think you were very smart but I think it was you being smart rather than the GPS that made the difference
What I'm not clear about is why you think the GPS was significant he the judge expressly said it wasn't and gave a perfectly clear rationale for his ruling which didn't include it.
Of course he's not going to set a legal precedent, he specifically admitted to not understanding it! What's he going to base that on? "I didn't understand what he was saying but that the nice man had a mighty smart looking phone."
Or are you suggesting that he did understand it and was lying? I don't see a judge doing that over a speeding ticket - they tend not to be big on lying, they just make the ruling so specific it can never apply anywhere else or expressly say that they don't feel this creates a precedent.
Technically, GPS uses both pseudorange and doppler data as an input. These are usually combined with the previously measured position and speed using a Kalman filter. Speed is generally more accurate than position (to the extent that it makes any sense to compare them) because pseudorange errors tend to change comparatively slowly. Of course how the receiver outputs the speed is up to it, but since it falls out of the position calculation for free it's unlikely many will be storing straight delta position/delta time.
Having said that, it's not especially strong evidence since it's pretty trivial to fake. However, in this case the title is correct: it contributed to him getting off because it gave him the confidence to challenge the ticket.
Sure it's easy to fake, but you are under oath. You can stand up there all day and say that, to the best of your knowledge you were not speeding and not perjure yourself. If you get up there with forged documents and get caught, that's something else entirely. So, they are not iron-clad evidence, but they should be pretty good.
My GPS, right now, has me clocked at a top speed of 273mph. I haven't a clue how that happened, but I'm sure as hell not bringing it to court to prove I wasn't speeding.
I no longer have the smart phone I used when I got caught, but my HTC EVO is actually quite accurate. I've pulled up my current speed while in a car (not at the wheel). It was spot on with the number from the car's dashboard.
On that note, my father has a BlackBerry smart phone and his Endomondo GPS tracking app states all sorts of weird things. He went for a few mile long hike and it thought he traveled a few hundred miles across the San Francisco Bay Area. (And yes across the bay.)
This is silly and dumb. GPS doesn't measure average speed. GPS measures location. Speed is calculated. It's calculated over the entire run - average speed - and it can be calculated between any two location measurements - which can be very close to instantaneous speed. Radar guns measure location too, for that matter - distance from the gun is measured at two instances, and speed is calculated. There's absolutely no inherent reason why GPS-based speed calculations are any less reliable than a radar gun. The better GPS systems update their position 5 times per second - far more precision than is necessary for good vehicle speed readings.
Can you show an example? I can't imagine what signal it would be calculating a doppler shift on, that could be more accurate than the positional data it computes. Most of the satellite signals -- certainly the strongest -- will be high overhead. Thus the signal path is essentially perpendicular to your direction of travel, and doppler shift wouldn't be significant.
Seems to me it won't be long til GPS units simply include a six-axis accelerometer, since acceleration can be directly measured without need of GPS and since such tech is cheap and already in both smartphones and game systems like the PS3 and Wii.
This will allow for far more precise tracking of your speed at any given moment.
Except that integrating any real world signal tends to introduce drift due to noise in the input signal. If you have a smartphone, try writing an app that does exactly what you propose; you'll soon find that it's impossible to get the "speed" to zero out. (Either that or you have to filter the data, which will cause other fun errors like your speed drifting toward zero.)
I thought about this as a complication, but my assumption was that this would be a solvable technical problem. Is it really not feasible to add an accelerometer to the GPS data (which does include altitude), and end up with at least somewhat more precise data?
You can feed the accelerometer data into the Kalman filter as well. However, since it's much more noisy than the GPS data, it won't give you any real benefit.
Where people would like this is to do dead reckoning when a GPS position isn't available (e.g. in tunnels). However, it turns out that it is completely useless for that, for the exact reasons the GP describes.
Actually, an accelerometer is far, far less precise because something like going up a slight incline results in a pretty significant change in the horizontal acceleration but a comparatively small change in the vertical acceleration (which is easily lost in the noise). The rotation caused by starting to go up a hill is also so tiny that it is completely lost in the noise.
The parent post already noted that the GPS doesn't know your instantaneous speed, just the average speed since your last reading. If your signal was blocked by trees, buildings, bridges, (not to mention your car itself), you can go at least several seconds without a reading, and what happened in between those points is unknown to the GPS, except for total ground covered. And that's even before you account for GPS inaccuracy, which is ~3m in optimal conditions.
In my experience, those outages don't tend to be frequent on main roads, where there is usually an unobstructed sight-line to the GPS satellites. Sure, it's possible that this dude floored it, hit 50-60mph for a second or two, slammed on the brakes leaving rubber all over the pavement, slowed to 15mph for a while to make the averages all work out, and proceeded on his merry way at 25mph.
This seems like a non story to me. The judge did not confirm at all the GPS data affected their decision.
However, I have used GPS data successfully in a somewhat similar situation. I was riding my bicycle to work and got hit by a car that was pulling out of a driveway. My GPS recorded the entire incident and showed quite clearly that the car pulled out and hit me well after I had already ridden pass the driveway, showing they just plain weren't looking (and not the other way around). The whole incident ended up in my favor.
I run at least one logging GPS in my car at all times for OpenStreetMap mapping. As a result, I've asked several lawyer friends about this situation should I ever be cited for speeding. Just about everyone has said that the GPS data would most likely be overlooked because it can easily be faked (or at least the decision makers have that perception) and/or judges don't know about it (so they default to ignoring it).
Another problem with GPS is the accuracy (or lack thereof). Sometimes you get a good GPS signal (e.g. outside, clear view of the sky etc.), sometimes you don't, and you position could be off by 10m. Some GPS store the accuracy of each track point (e.g. VDOP and HDOP), some don't. If your GPS doesn't store the accuracy, then someone could claim your GPS is off by 20m, and hence you were speding (or the data is unreliable).
I'm glad the judge & author pointed out that it wasn't necessarily the GPS that got him off: the chain of custody could probably have been successfully challenged. But it's darn good circumstantial evidence.
Warning: probable abuse of lawyerly language in above post.
Basically the only help your phone provided is to give you guts to defend yourself in court. The data you obtained with google tracks has as much legal authenticity IMHO as data you could pull out of your behind. But the fact that you asked the officer the right questions and he didnt have the right answers is in my opinion why the judge decided in your favor.
Not long ago, I got pulled over and discovered my proof of insurance card was out of date. I was able to use the iPhone app of my insurance company to load up a PDF of the most recent copy and prove that my insurance was current. The cop was amazed that I could do this. No ticket. :)
My uncle was driving a truck a few years ago and hit a woman who walked in front of his vehicle. It was not his fault because the woman stepped out looking the wrong way, and the wet weather and short distance meant it wasn't possible for him to stop in time.
In this instance, the GPS tracking data was used by the police to verify that he was not travelling faster than the speed limit. The data backed up his statement to the police and he therefore wasn't considered negligent or liable for the accident in any way.
Technology like this certainly has its benefits, particularly when the presumption of guilt is so often on the driver in this kind of situation.
I can't remember specifically the example, but there was a recent case where someone recorded the conversation with a police officer without the police officer's knowledge or consent. This ended up getting the person in a lot more hot water than the original issue. If someone could provide specifics, would be appreciated.
In any other state, if you (as the recorder) are aware that you are being recorded (ie, you're recording your own conversation with someone else), it's legal.
Really? All I can find[1] seems to indicate all parties need to consent:
"4. The term 'interception' means to secretly hear, secretly record, or aid another to secretly hear or secretly record the contents of any wire or oral communication through the use of any intercepting device by any person other than a person given prior authority by all parties to such communication..."
They usually don't have to believe what the law is when many citizens will easily bend at the sight of officer intimidation because they don't actually know the law.
In at least three states, it is now illegal to record any on-duty police officer.
also
Illinois, Massachusetts, and Maryland are among the 12 states in which all parties must consent for a recording to be legal unless, as with TV news crews, it is obvious to all that recording is underway.
Edit: to my knowledge, these are based on outdated wiretapping laws intended for telephone conversations.
Some phones, at least in the Droid line, have car mounts which include chargers; he mentioned a car mount in the article, so it's quite likely using it as a GPS was having a positive impact on battery life in this case!
I got out of a speeding ticket in 2004 because the officer had allowed his radar certification training to lapse in 1982. The guy before me in court also got his case dropped when the judge found out the officer hadn't been radar certified.
This guy's GPS data was a novelty. No more a deciding factor in the judgment than his choice to wear business attire.
