Schneier (my hero) has an interesting post where he points out more problems with trusting proprietary software - some bugs in a breathalyzer. His comment:

This is important. As we become more and more dependent on software for evidentiary and other legal applications, we need to be able to carefully examine that software for accuracy, reliability, etc. Every government contract for breath alcohol detectors needs to include the requirement for public source code. "You can't look at our code because we don't want you to" simply isn't good enough.

Basically they found a stack of problems with the software. The full story is up here: http://www.dwi.com/new-jersey/state-v-chun/

And it includes classic bits like:

Base One, however, did an extensive evaluation, finding 19,400 potential errors in the code.

2. Readings are Not Averaged Correctly: When the software takes a series of readings, it first averages the first two readings. Then, it averages the third reading with the average just computed. Then the fourth reading is averaged with the new average, and so on. There is no comment or note detailing a reason for this calculation, which would cause the first reading to have more weight than successive readings. Nonetheless, the comments say that the values should be averaged, and they are not.

12. Defects In Three Out Of Five Lines Of Code: A universal tool in the open-source community, called Lint, was used to analyze the source code written in C. This program uncovers a range of problems from minor to serious problems that can halt or cripple the program operation. This Lint program has been used for many years. It uncovered that there are 3 error lines for every 5 lines of source code in C.

Fascinating stuff. While I'm all for drunk drivers getting hauled off the streets, its super important to know the tools being used to do them are actually working properly.

Wait, you want companies who create the software/hardware for breathalyzers to release their source code?

I think I might go call Nintendo and see if they'll give me the source code to Brawl to check for errors.

Wait, you want companies who create the software/hardware for breathalyzers to release their source code?

why not?

I think I might go call Nintendo and see if they'll give me the source code to Brawl to check for errors.

its a little difference. the police use the device as evidence, then we should have the right to screwtanise* the eveidence.

*spelling.

last edited by mooby at 12:17:02 14/May/09

Nintendo's games aren't use to decide whether people go to jail. This is a pretty big deal, and any decision making process should be made public. Although in law, do judges have to explain their thought process for making a decision? Nope.
Because it doesn't matter whether the law gets it right or wrong, as long as a majority of people believe the government is doing something about a problem, then that is all they care about.

Pretty interesting stuff. I'm not surprise that their code is s***house after having to maintain a number of systems written by "experienced programmers" who are supposed to know their s***.

I really find the whole 'must be opensource' argument to be BS in most cases - why not go a different route:

The client writes (or hires someone to write) the test suite to which all revisions must pass a black box test via an interface? Payer give it data in, developer gives data out, and the payer decides whether it meets their requirements. If you absolutely must see source code, sure, requiring them to reveal the source of their own tests is fine. But most frequently software is just poorly tested. No, developers should not be the only ones who write tests for their own code - I'm currently trying to push for me to never write the tests for the code I write - others do that, and I do the same for their code.

19,400 'potential' errors in the code? I call bulls***. It's a breath tester, not the Linux kernel.

you dont get convicted off a breath test anyway:

Why bother writing down what laws and previous cases this country has? Just set up a 'black box court' and throw random anecdotes at a Judge and see what their response is?

Why bother writing down what laws and previous cases this country has? Just set up a 'black box court' and throw random anecdotes at a Judge and see what their response is?

...
...
...?

I don't see the problem with this.

Spoiler:
:)

Open source isn't necessarily the answer. I write code that is regulated and has to go through a number of approval processes, both internally and externally, before it can go into production. We don't need to open source our software, and it has enough controls on it to ensure its fair and works as advertised.

The problem is that the code may not be doing what it is specified to do.

Opening the source is just one strategy to address the problem.

who cares anyway, once you blow over they check you again 30 minutes later
if you blow over 0.05 again, you go back for a blood test

fail that and -then- you're screwed

Yeah it can't make a rounding error if you've had zero alcohol.

Wait, you want companies who create the software/hardware for breathalyzers to release their source code?

I think I might go call Nintendo and see if they'll give me the source code to Brawl to check for errors.

our poor, poor gene pool

If you have not been drinking, or have literally only had a max of two standards, and blow higher than .05, surely you can ask to redo it on the spot? I wonder what rights you have in these situations??

This questions the reliability (test-retest scores should be the same). If you blow .05 and then a few seconds later blow .01, you'd be very concerned about the technology. If you have a breathalyzer at your local RSL, spend a few bucks after a few beers and measure yourself a few times in a row with only a minute or two between each turn and see how reliable the equipment is.

everyone knows that: drink drive & survive

If you have not been drinking, or have literally only had a max of two standards, and blow higher than .05, surely you can ask to redo it on the spot? I wonder what rights you have in these situations??

I already answered that.

if you blow over 0.05, you immediately get out of the car and either sit in the booze bus or in the back of a cop car for 30 minutes*
after 30 minutes you are asked to blow again

if you blow over 0.05 again, you are taken to have blood drawn - at which point the test becomes less about the equipment anyway


* = unless you're obviously legless, in which case they just take you straight back for the blood test

I've heard so many stories of people who were 'obviously legless' that turned out to actually be a diabetic, or have a personality disorder, the downs, or something else.

This questions the reliability (test-retest scores should be the same). If you blow .05 and then a few seconds later blow .01, you'd be very concerned about the technology. If you have a breathalyzer at your local RSL, spend a few bucks after a few beers and measure yourself a few times in a row with only a minute or two between each turn and see how reliable the equipment is.

if you still have alcohol in your mouth (ie you just had a drink) you will get results all over the shop:

This is similar to the Radar clause in court. Ask to see the device service record and proof of accuracy and the court just closes the case cause the police will not allow public scrutiny of the radar gun system. If the police had a better open-source or atleast public oversight into the radar system, less hoons would get out of court for free cause they did 200km/hr in a 60zone and the cops don't want to give access to their documents.

If you have a breathalyzer at your local RSL, spend a few bucks after a few beers and measure yourself a few times in a row with only a minute or two between each turn and see how reliable the equipment is.

Those ones are, afaik, completely different hardware to the ones that the police use.

Haha Billy was it with you that I was in a cab with and we had that crazy driver that was trying to sell us his breathalyzer products? I can't remember (cuz I was drunk). He was hilarious.

Someone I know bought a police-quality breathalyzer; I think it was almost a thousand bucks. I dunno the maths of how they work as opposed to the cheap s***ty ones you can buy for $20 at a gas station but I can certainly believe there's a difference.

I had a breathaliser I actually bought off someone on OCAU and if you blew hard enough you'd always be 'drunk'!

The new qld cop ones have a GPS device built into them, which they don't seem to be able to operate without.

Just need a white noise generator at the right frequency and it won't be able to get a lock.

I already answered that.

if you blow over 0.05, you immediately get out of the car and either sit in the booze bus or in the back of a cop car for 30 minutes*
after 30 minutes you are asked to blow again

if you blow over 0.05 again, you are taken to have blood drawn - at which point the test becomes less about the equipment anyway


* = unless you're obviously legless, in which case they just take you straight back for the blood test

you only have a blood test if you refuse to blow in the bag or request it.

you get done once. they take you back to the station or to the booze bus.
back at the station you re-do a blow in teh bag scenario but with a freshly calibrated machine. (a lot bigger and is connected to a computer so they print out a thingop saying it is working properly. then do another test and print out a thingo saying ..yes you are f***ed me ole china)

blood tests arent the norm. only in certain situations.

Definately request the bloodtest if you've already come back > 0.5BAC, at least if you know you are borderline.

An RBT device is pretty inaccurate, so theres a chance you'll actually be under 0.5BAC. They probably calibrate the devices as such so that they get false negatives more than false positives though, but its definately worth going again if you are already catching the bus for 3 months.

If you are genuinely drunk and you request the blood test though, you might get bumped up to the next level (where it becomes a more serious crime). I've no idea what that limit is in QLD though.

Heh I just found the business card from the cab driver I had with the breathalyzer company buried on my desk - www.drinkingmate.com.au if anyone cares

Although in law, do judges have to explain their thought process for making a decision? Nope.

Yes they do, and their decision can be overturned by a higher court or simply told to "try again" if they make a decision and their process was wrong in the higher court's point of view.

It was a rhetorical question Nathan! Judges often assert "I don't believe that scenario", or "I don't see why the police would be wrong" etc.... You'd have to have a lot of spare time, money, and a great lawyer, to try to get an appeal on the grounds that a judge didn't talk anything through.

You can beat a Breathalyzer by placing 2 very strong magnets in your mouth.

and you could probably beat it by drinking cyanide too Faceman! seriously, the original test, is just to establish a baseline, if its over 0.05 as said, they take you to the station or booze bus, and within two hours they test you again. and based on that reading then your charged. the Transport Operations (Road Use Management) act, can get very technical. especially when it comes to s.79(c)1. which deals with drink driving.