No GPS = Not admissable as evidence in UK courts?

[DavidUK]

Just saw a post on a car forum saying this.

Surely video of an incident would be admissible without GPS info?

Any UK legal eagles here with the answer?

 

[kamkar]

I cant see that being true, if thats the case then regular CCTV footage should be inadmissible too.

If it is on "tape" then i cant see there is any way around it, stupid is what camera see as my momma use to tell me

 

[Nigel]

More like the other way around!

The GPS recorded by dashcams isn't accurate enough to be accepted as absolute proof of speed, if speed is needed then it will be calculated from the frame rate and the movement per frame to give reasonable proof. GPS can probably be useful but it is not proof.

In general the courts will accept any evidence if an expert will declare that it has some accuracy and it is not proven unreliable by another expert.

 

[2000rpm]

My insurer was happy to accept non-GPS-stamped (but date/time-stamped) footage from my bump earlier this year.
As far as courts are concerned, I would have thought that most dashcam footage would include easily identifiable unique buildings, road signs etc in the same clip leading up to the incident making GPS merely a confirmation of the obvious.

On one dashcam it said 2 metres accuracy of the GPS unit.
I was once able to have a dashcam speed stamp jiggling between 1-3mph while stationary due to minor inaccuracies in position information and overhanging trees and nearby tall buildings blocking the best of the GPS signal from the satellites.
Also on bends and hills a speed stamp will be inaccurate (usually under-reading).
So even with a GPS-derived speed stamp it's not possible to conclusively prove someone was speeding unless it is significant speeding. The time it took a vehicle to pass between two fixed roadside objects would allow accident investigators to approximate the speed but I doubt they could get closer than 95% accurate.

 

[Rajagra]

Unless GPS data is embedded in some digitally signed way that is impossible to forge, then I think the GPS stamping is the least reliable part of the video footage.
The credibility comes from the footage itself. Few of us have computers capable of generating CGI to show what we would like footage to show.
GPS data is icing on the cake.

 

[SawMaster]

Unless in the midst of farm fields with crops growing, almost any other place on land is readily identifiable in pics and vids. Plain pics and vids have been used as evidence everywhere for a long time with none of those 'extras'. Law doesn't always follow common sense but it's never counter to the obvious and clear. When someone says something like this I'm going to ask them to prove it and to also prove there were no extenuating matters involved bearing on it.

This has my BS meter reading full-scale bending the needle If it's true there's more to it than is being said and some very pertinent facts are being concealed by someone whose veracity is highly questionable until proven otherwise

Phil

 

[dash riposki]

How would you prove the GPS was accurate, anyway?

I had a good laugh the other day because a driver with the company I work for got a ticket for 67 in a 55, and he claims he was only doing 65....and the GPS connected to the company communications/log terminal in the truck would prove it! I think the safety department laughed at him when he called and wanted the data, also.

 

[Daleg]

Just saw a post on a car forum saying this.

If it's on the Internet....it must be true right? Bonjour...
Neighbor told me cats have imminent domain...he read it on the Internet and says it's a fact...wonder if that's why his cat always looks at me like he doesn't give a rats ass when he lounges in my yard.
The Internet.... the disinformation highway...

 

[Sunny]

So they want to discuss who's right blaming each other rather than looking at the videos?

 

[Nigel]

How would you prove the GPS was accurate, anyway?
...

Some GPS receivers record horizontal and vertical accuracy values in the logged data which I think are probably good enough to use in court as reasonable proof if accompanied by an appropriate statement from an "expert". However I've never seen a dashcam record these in the gps data and I have seen obvious substantial errors in the readings, so dashcam gps is useless as proof, it is only useful as a guide during the investigation and then you get the proof by analysing the video.

Unless GPS data is embedded in some digitally signed way that is impossible to forge...

Having it digitally signed is not going to make any difference since there is no way to know that someone hasn't found a way around the digital signing!

Normally dashcam footage is going to require the person who recorded it to state that it is accurate in court, the court will then accept it as good evidence unless someone else can show that it is not accurate or that it is misleading.

 

[jokiin]

Even the equipment used by police needs regular scheduled recalibration and documented evidence of that having happened to be admissible as evidence, no consumer device is going to stand up to scrutiny if accuracy is being questioned

 

[Rajagra]

Having it digitally signed is not going to make any difference since there is no way to know that someone hasn't found a way around the digital signing!

By digital signing I mean a calculated value using encryption techniques that is based on both the visible data and a private key. The whole point of it is that it is trustworthy - for now. Once it is cracked it becomes useless.

But that's academic because I doubt GPS uses such signatures, and even if it did it isn't recorded by our cash cams.



Sent from my tap-to-talk using Tapatalk

 

[Nigel]

Even the equipment used by police needs regular scheduled recalibration and documented evidence of that having happened to be admissible as evidence, no consumer device is going to stand up to scrutiny if accuracy is being questioned

Maybe that is why the police don't use gps - there is no way to calibrate it, much better to use an analogue speedometer that is affected by tire pressure and temperature but which can be calibrated!

I did once use a calibrated gps receiver but I don't think it's atomic clock would have fitted in a police car.

 

[jokiin]

Maybe that is why the police don't use gps - there is no way to calibrate it.

regardless of how accurate people think their GPS is the reality is the system we all use is not all that accurate, it is however free to use and there is some error correction and multiple signal interpretation going on in a lot of systems which helps them offer improved accuracy from the information available

 

[SawMaster]

With the proper equipment used correctly GPS can be extremely accurate, but not in rapidly-moving mobile or consumer-grade applications. It's generally within a meter or two for location and within a few KPH for speed so for glaring discrepancies it can be useful, especially with corroborating evidence, but not for fine details. For the last decade or two US DOT requirements for car manufacturers speedometers allow it to indicate you are going as much as 5 MPH faster than you really are, but not any amount slower than you're actually going. Previous to that there was a error percentage applied to them so you could account for a few MPH over the limit, and that's why in the past most PD's here didn't ticket for less than 5 over. Now if your speedometer says you're speeding then you are

IIRC the EAA now allows GPS to be used for most private instrument flight navigation though the FAA still doesn't. It's good enough for that since there is always a requirement for visual confirmation and cross-checking to normal flight instruments, and planes are kept spaced well apart for safety when airborne. Performance boaters have also found GPS speeds inaccurate unless taken over long distances though I can't remember exactly what causes that. I've found my ancient GPS unit to be accurate for speed on the highway by timing mileposts over a ten-mile distance but that isn't a proper calibration.

None of this affects the video portion of a dashcam though
Phil

 

[Nigel]

By digital signing I mean a calculated value using encryption techniques that is based on both the visible data and a private key. The whole point of it is that it is trustworthy - for now. Once it is cracked it becomes useless.

OK, I've thought of a way around it!

When you calibrate a GPS receiver, you do it using a GPS simulator which transmits a signal to simulate the satellites. You can put whatever information you want in that signal so I could produce a GPS signal that always gives a speed 10mph less than my actual speed and transmit that to the dashcam for it to be recorded and correctly digitally signed. I think I remember James Bond coming across a similar device that had put a warship off target...

 

[DavidUK]

Excellent!!

Thanks for all the replies. I guessed as much!

 

[DT MI]

OK, I've thought of a way around it!

When you calibrate a GPS receiver, you do it using a GPS simulator which transmits a signal to simulate the satellites. You can put whatever information you want in that signal so I could produce a GPS signal that always gives a speed 10mph less than my actual speed and transmit that to the dashcam for it to be recorded and correctly digitally signed....

So when you're sitting at a stop light it would show you traveling in reverse at 10MPH?... or would it show a speed of -10MPH?

 

[Nigel]

So when you're sitting at a stop light it would show you traveling in reverse at 10MPH?... or would it show a speed of -10MPH?

It would be show +10 mph at a 180 degree angle to original trajectory, unless I made it just a little more complex

Think there might be a market for such a device?

 

[jokiin]

unless I made it just a little more complex

your area of expertise as luck would have it