Breathalyzer Source Code Analysis Uncovers Ancient Technology!


If you've been arrested for a DUI charge, you probably took a breath test. As technology has increased over the years, breathalyzers have become one of the main components of the testing performed by law enforcement authorities, and thus an important part of the state's case against DUI offenders.

Recent cases in Florida, Minnesota and New Jersey are turning to examination of the source code that programs the breathalyzer used in DUI cases in those states. However, this defense has been difficult to pursue up to this point, largely because of the protests of the companies that make the breathalyzers.

Many of these companies claim that revealing the source code in their breathalyzer devices will hurt them commercially, since the code contained within the devices is a trade secret. Public disclosure would allow other companies to copy or steal their code and pass it off as their own.

In a recent Minnesota case, for example, the Minnesota Supreme Court has ruled that the state must turn over the source code of the Intoxilyzer 5000EN, which the state uses as the standard in all of its law enforcement offices, to a defendant in a DUI case.

However, the state and the breathalyzer's manufacturer, CMI, Inc., are engaging in legal waffling that has ended in other cases with the results of the breathalyzer being thrown out. The state has denied that it has the authority to disclose the source code, citing confidentiality of proprietary code, while CMI's defense has been the standard corporate defense of proprietary code.

However, in a watershed case in New Jersey for those who have been pushing for companies to disclose source code, a judge order has resulted in actual analysis of the source code of the Draeger AlcoTest 7110 MKIII-C.

After two years of attempts, and countless refusals and motions by the state prosecutor, DUI attorneys were able to not only receive a judicial order to reveal the source code, but were able to have expert analysis of the code by a New Jersey-based technology company, Base One Technologies.

First, in response, to Draeger's claims that the source code was a trade secret-an argument that virtually every breathalyzer manufacturer has used to deny court orders for disclosure-the experts found that code contained only general algorithms, that "the code is not really unique or proprietary."

What Base One Technologies further found when the source code was analyzed is astounding. After studying the code and using several industry benchmarks for comparison, the technicians at Base One identified a total of 19,400 potential errors in the code!

Their summary recommendation is as follows:

  • "There is no doubt that the Supreme Court should declare this machine to be unreliable."

Many of the code's functions, Base One suggested, could lead to errors in the reliability of the data gathered from the breath test. For instance, readings performed are averaged together with new readings, giving undue weight to a first reading, when all readings should have equal weight in determining the BAC.

Also, the Draeger AlcoTest device takes an initial airflow reading at start-up to use as a baseline measurement. However, there is no testing or accounting for changes in air flow that might be different from this arbitrary baseline. Thus, a range of possible values may be inaccurate simply because the initial reading may discount it.

The values for the readings, which have the possibility of a range between 0 and 4095, are divided by 256 within the machine function, and so there are only 16 possible reading grades, not nearly the level of precision required by a breath test device.

Overall, the experts had major problems with the structure of the code itself as well, which they deemed would not pass U.S. software industry standards. Many parts of the code were added at later dates, exhibited signs of "trial and error" approaches, were added as extensions to main modules and inserted "temporarily" into code streams. This created a patchwork design that does not function smoothly nor make design testing accurate.

Absurdly, the experts found that the software on the 7110 is written an Atari-style chip, using 15-to-20-year-old technology and 1970s computer coding techniques. Maybe the people at Draeger shouldn't have been so quick to claim that the technology in the AlcoTest 7110 was theirs!

Needless to say, the state of New Jersey will have its hands full trying to recover from this blow dealt to their system for DUI conviction. It will certainly be difficult in the near future for them to use BAC results from breath tests using the Draeger AlcoTest device given the findings by Base One.

If you're preparing a case to defend your DUI, you should know that you may have several options for defending a DUI, and one of the most common is to dispute the findings of the breath test.

Breath tests are based on formulas for an "average person," and drivers who can prove that they do not fit this standard profile in some way-weight, height and body mass index, as well as medical conditions that may affect blood alcohol content (BAC)-sometimes successfully move to have the results of a breath test suppressed or argue its validity to a judge or jury.

People who have been exposed to chemical compounds or environments that may contain those compounds may also show inaccurate breathalyzer test results, falsely indicating the presence of alcohol in their systems.

Other defenses involve proof of misuse of the breathalyzer, improper handling of data, or a dispute of the proper function of the breathalyzer or BAC analysis machine.

And, now, this process will likely include requesting the source code of the breathalyzer to be revealed, a move which has been fought by states and companies for years, but will prompt states to take a new look at this vital part of their conviction process and breathalyzer precision and reliability.

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