Intoxilyzer Source Code

Many times, clients ask me how the intoxilyzer determines their blood alcohol content. I try to explain the mechanics of it, the theory of it, and the science of it. The problem is that the manufacturer of the machine, CMI Inc., will not release the source code of the software in the machine. For all we know, the machine generates random numbers that essentially say you are guilty. It is interesting that many people will swear up and down that they only had one or two drinks. When they take the test, they end up being way over the limit. There are some serious questions about this machine. Why would the manufacturer be afraid of releasing the source code? Their argument is that it is copyrighted. I can see that argument, but they will not release the source code even under a protective order that will prevent the code from being released to anyone else and can only be used for analysis. Maybe CMI is afraid that their conviction machine will be revealed for what it is, a box that makes them money and convicts innocent people.  This machine uses a processor like computers do.  However, it is not state of the art.  The processor is the Z80 chip.  This processor was used in the Atari that I played with 30 years ago.  Here’s a story about litigation over that source code.

Breathalyzers Come Under Fire in Court

Posted Aug 10th 2007 2:59PM by Terrence O’Brien
Filed under: Car Tech
Breathalyzers Come Under Fire in CourtSome while back, certain residents of Florida charged with DUI managed to get a court to hand them over the source code of the breathalyzer that had "proven" them to be drinking and driving. Now, in another victory for drunks everywhere, Dale Lee Underdahl of Minnesota has filed a similar petition and won.

What is source code and why would you want it? Breathalyzers are basically computers with blow holes, and the source code is what makes them run. That source code is what sends people to jail. The defendants in these cases simply want a good look at their accuser. As Underdahl’s lawyer said, "for all we know, it’s a random number generator."

The breathalyzer in question in Underdahl’s case is the Intoxilyzer 5000EN, built by CMI, one of nearly a dozen manufacturers of devices used by law enforcement. CMI’s Intoxilyzer is used in more than 20 states. What’s frightening is that the 5000EN is apparently based on the ancient Z-80 processor, which powered the Radio Shack TRS-80 desktop computer … which went on sale in 1977. CMI has also been accused of making uncertified changes to the machines, and had to issue a recall due to faulty software.

In other words, Underdahl may be on to something. But to be on the safe side, maybe next time he should just call a cab.

Judge tells breath-test maker to release code
SARASOTA — The company that manufactures the state’s drunken-driving breath-test machines must turn over the computer code that runs the machines or face stiff fines, a county judge has ruled.

Defense attorneys have argued that having their experts examine the Intoxilyzer 8000’s "source code" is the only way to ensure the machines correctly calculate a driver’s blood-alcohol content.

The Intoxilyzer 8000’s first glitch was discovered in April, a month after it was implemented, when state officials realized it failed in certain situations. The state then upgraded the software in machines across the state.

In Manatee and Sarasota counties, more than 32 DUI cases are delayed because Kentucky-based CMI Inc. has not responded to a subpoena ordering the company to turn over the source code for the Intoxilyzer 8000, Sarasota County Judge Kimberly Bonner wrote.

"The failure of CMI to comply with this court’s subpoena has created a tremendous backlog of cases," Bonner wrote.

The judge found the company in contempt and gave it 20 days to turn over the source code or it will be fined $3,200 per day, or $100 per case that cannot move forward in the case. Other cases not covered in the ruling are affected as well, the judge wrote.

The company has said that the code is a trade secret. It did not respond to the Sarasota County case, but took the issue to the Daviess District Court in Kentucky.

A judge there quashed the subpoena for the source code. But Bonner said that order has no jurisdiction over Florida courts.

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