GPS Used As Defence In Radar Speeding Case

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."

Comments

Video Evidence

[ZERO1ZERO]

I've often thought it would be a good idea to have a constant video recording your driving, like the police camera setups. This could help clear up who to beleive at the scene of accidents, because of the video.

Plus it would be cool to have onboard footage of your driving for analysis and review.

Re:Video Evidence

[billcopc]

Yep, police work is only performed where it matter$, aka speed traps and deliberately low limits. Saving lives is not a profitable business, which is why no matter what you do (or don't do), if a cop shows up, you get a fine.

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

[drsmithy]

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.

Open source GPS?

[KillerCow]

But will he be able to produce the source code for the GPS when the police request it to check its accuracy?

Breathalyzer Source Code Revealed
Closed Source -> Charges Dismissed?

I have used this

[www.sorehands.com]

I used the GPS defense when pulled over.

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 .75 mph.

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.

I work for the radar company...

[crazybilly]

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. But for what it's worth, I use Linux on my machine at home, hehehe.