Slashdot Mirror
Florida DUI Law and Open Source
pete314 writes "A Florida court this Friday will hear arguments in a case where the accuracy of a breathalyzer is being scrutinized because the manufacturer refuses to release the source code. A state court ruling last year said that accused drunk drivers are entitled to receive details about the inner workings of the "mystical machine" that determined their guilt, and defense attorneys are now using that ruling to open up the device's source code.Is this part of a larger trend? With software bugs being a fact of life, consumers and organizations could claim that they need to be able to verify an application's source code before they accept that their calculations are accurate. Think credit card transactions, speed detecting radar guns, electronic voting machines..." Here is our previous story when this first became an issue in Florida.
One of the easiest ways to get a speeding ticket overturned/dropped (at least in the UK) is to request all of the calibration reports for the particular camera/radar gun used to take your speed.
If the reports cannot be produced or are older/outside the statutory testing period, then the data produced by the machine will not hold up in court, and so the case will be dropped.
In some cases, the police simply cannot be bothered/do not have the time to do all of the necessary paperwork, and so the case may just be forgotten/ignored.
I don't know if this could be applied to a breathalyser, but it would be an interesting to see what would happen...
[All Your Fish Are Belong To Us]
With regard to some defense attorneys, I suspect that you're dead right.
That said, if I was "convicted by machine" I would want to know:
o That the machine was accurate, and had been maintained in such a condition as to maintain its accuracy.
o That it was calibrated and tested regularly.
Years ago I used to work for a company that made infrared milk analyzers, around about the time that the first infrared alcohol detectors replaced the "blow in the bag" crystals. The alcohol machines were much cheaper and appeared to be less accurate - they used one beam instead of the two (sample + reference beams) that I'd have expected and didn't appear to be maintained at a constant external temperature. However, they probably don't need to be that accurate - the milk analysers were accurate to 0.01 or 0.02% of a constituent of milk, but I doubt that only that much over the drink / drive limit is going to get you convicted.
When I was involved, the "software" side of infrared analysis (other than hardware control and display) was essentially correcting for inaccuracies in the hardware - making a series of measurements with known (independantly calibrated) inputs and changing the displayed result to match.
The fact that the software or the hardware has changed slightly since originally certified is irrelevant provided that the machine is regularly (independantly if necessary) tested and shown to be within the required level of accuracy. Software is also somewhat irrelevant if the machine can provide at-the-detector measurements before they are converted to "amount of alcohol in a sample", and allow that to be compared to a reference sample series.
For what it's worth, none of the software that I wrote for milk analyzers was ever "proven correct" in a mathematical sense, although it was of course tested in the normal sense.
Here in Australia, the road-side breath test (RBT) just gets you dragged to the police station, where they take a blood sample. It's the blood sample that gets you convicted, not the RBT... additionally, they take two blood samples: one for you, one for them.
Aren't blood samples used in the US? Do you not have that option?
In Australia the breath test is only used to indicate that a blood test is required, and can't be used to prosecute.
Of course this may give the driver's blood time to fall below the limit, but is far more accurate. To address this, the police sometimes have roadside blood testing vehicles (the booze bus).
I've built medical devices before. This is in essence a medical device. If this were being used in a medical laboratory for medical purposes, source code changes which were not properly recertified would void the FDA approval for the device. There's a reason for that.
It's a truism in software that you can't verify the absence of bugs by black-box testing, no matter how complete the test vectors. This is doubly true when the software is interacting with the real world, in a nontrivial manner.
Consider: The device undoubtedly measures a change in itself that occurs in response to the presence of ethanol. A voltage is produced, a current is seen, or a color change occurs in some sensitized material. Some chemical reaction occurs, and produces a detectable change in the device state. But because chemical reactions are susceptible to variation in temperature, in the age of the reagents, in the particular lot of the reagents, and in subtle machine-to-machine differences between reaction sites, the software for the machine must contain built-in adjustments for all of this. If you have a half-dozen linear adjustments that you have to make (not uncommon, in laboratory equipment), the six-dimensional test vectors that you have to check are massive. If you have a dozen such factors, you literally can't test enough combinations to be sure that every combination works. And even worse, you have to verify that the machine is in a known state at the beginning of such a test, and without access to the source you have no way of knowing.
The question isn't whether the machine can be made to work in a laboratory setting. The question is whether the machine worked this time, in the middle of the night, in an un-airconditioned drunk tank in God-knows-where, as the thirty-fifth breath test that night. If you don't have the source code, you literally can't possibly know what the chances are that it really worked.
As much as I hate drunk drivers, and as much as I think that the machines are probably pretty good, I'm with the defense attorneys here: produce the source, or stop pretending that this machine can produce proof beyond reasonable doubt.
The car type was a Datsun 120Y, clocked at 158 kph -- some details. The owner of the car stuck to her guns; she basically went to ridiculous lengths to try to hit that speed in her car (even hiring a professional race driver), without succeeding.
This triggered a massive review of all the Victorian fixed speed cameras, and the refund of a large number of speeding tickets.
The wall might have had a velocity of -4mph, but it would have a speed of 4mph.
in some way shape or form for the last 18 years, I can tell you that breathalyzers are tested regularly. Each agency that I have worked for/with has had its machine tested and calibrated on (at the worst) a monthly basis. Logs and printouts of the tests are kept for a period of time (last I remember it was 5 years, but that may have changed). The machines are tested against a predetermined and certified air/alcohol mixture, and sent back for recalibration if they fail to report a correct alcohol level past a very minute tolerance. The machines work. Any standards and training officer worth his salt can rip this defense to shreds with documentation on his agency's breathalyzers.
A BAC isn't really something depends on an "algorithm". Of course different people will have different BACs even after the same amount of alcohol - but that's irrelevant, since "DUI" is a measure of your BAC, not how much you've had to drink. The reason this is done is precisely /because/ different people have different metabolisms, etc.
It's well-known, for example, that women will blow higher on a breathalyzer than a man simply because they're generally smaller.
Of course they will, but that's irrelevant...
Similarly for LIDAR (laser speed detection), the underlying principle is using distance and time to determine rate. Sounds straightforward, as d = r * t, but how do you know you've got the right values for d? It's been shown that rapid movement of a LIDAR gun can cause even inanimate objects to register a rate. How do we know the LIDAR gun measured the distance your car traveled over a period of time, rather than the distance of your car at one point in time and the distance of some other reflective object (say, a much closer stop sign) at a different point in time?
In theory, the software in the machine discards "anomalous" readings (eg: ones that would say a car is travelling at 500km/h).
At the distances in question, we're talking sharpshooter skills as a requirement for using a LIDAR gun, but it seems that every cop on the force has one. Can they expect us to believe that every cop is a sharpshooter, or that several cups of coffee won't induce shaking in the cop's hands that could cause false readings?
It's even worse than that - at 500m the "beam spread" on a LIDAR is 1 - 1.5 metres, so it's quite feasible that the LIDAR is making it's calculations based on one part of the beam that bounced back from, say, the driver's sunglasses and another that bounced back from the numberplate (or one part on car A and another part on car B behind it).
That said, LIDAR's aren't *ridiculously* inaccurate - if they read a speed, it's almost certainly going to be correct to within +/- ~10km/h. So if you get pinged doing 150km/h in a 100km/h zone, trying to use the inherent innacuracy of the LIDAR equipment as an excuse is pretty questionable (although it may well work, legally speaking).
Then again, given how ridiculously low the average highway speed limit is, if you can get off (and you weren't driving dangerously), more power to you.
It's a good precedent, forcing the breathalyzer source to be opened to inspection, but the assumption is still that the underlying algorithm is accurate when it's not.
But it is. The data might not be 100%, but the algorithm is fine. Determining an object's velocity given it's displacement over a known timeframe is a pretty well-tested algorithm :).
I don't understand why courts continue to rely on technology such as the breathalyzer or the LIDAR gun when there are better, proven tests that could be used instead (blood tests, RADAR or pacing with a calibrated speedometer).
Because blood tests are hard to automate and administer quickly (and in some jurisdictions might not be doable by an officer on the side of the road for legal reasons)[0], because LIDARs are more accurate, less error-prone and less avoidable than RADARs (hence the reason LIDAR replaced RADAR) and because pacing with a calibrated speedo implies significant possibility for human error, not to mention vastly cutting down on the number of vehicles than can be checked per hour.
[0] At least in Australia, a breathalyser test can't get you convicted - it carries no legal weight. A positive breathalyser test is simply justification for a blood test to be taken. Only the results of the blood test can be used in court.
It is called the Government Printing Office. The GPO publishes books, magazines. posters and CD-ROMs in hundreds of categories. Titles like "The American Practical Navigator" have been in print for two hundred years. U.S. Government Online Bookstore
Here in Austria its the same, and in Germany too.
But it has always been that way, I don't think breath tests are accurate enough to prove a case in court. They are only an indication if a blood test is needed or not.
And often somebody is just above the limit in the breath test and just below the limit in the blood test.
Still mostly the same down here. They just recently passed a weak open container law in NOLA. And the original version was ONLY for the driver of the car...so, if you were getting pulled over...just hand your drink to the passenger. I think they now have something about any open container in a car, which is stupid IMHO....who cares if the passengers have a beverage?
But, in New Orleans proper...there is no open container law while walking the streets..you can still get a 'to go' cup at a bar and walk around about anywhere you want with any type of alcoholic beverage.
Light travels faster than sound. This is why some people appear bright until you hear them speak.........