The State Miscalibrates Its Breath Alcohol Machines

Posted On October 02, 2023 Charles Ramsay

Last week, I told you about how the Bureau of Criminal Apprehension hides important calibration data on their breath alcohol machine certificates. They shouldn’t be calibrating their breath alcohol machines with a zero calibrator. 

But they are. 

And they’re hiding it on their certificate of calibration.

Both the American Academy of Forensic Sciences (AAFS) and the Scientific Working Group for Forensic Toxicology forbid including a zero calibrator on a calibration curve.

But there’s another twist. The state isn’t using the required number of calibrators in their curve. According to the AAFS Std 055 - Standard for Breath Alcohol Measuring Instrument Calibration, the state must use six non-zero calibrators:

“A minimum of four non-zero calibrators, if measurement technology is linear or six non-zero concentrations, shall be used as calibrators if non-linear.”

The state’s breath machine, the DataMaster DMT, uses infrared technology. According to the manufacturer, this technology is “inherently non-linear.” This non-linearity can only be overcome “by performing a multi-point calibration.

Currently, the state only includes four calibrators. This is only valid if the state was using a linear method of testing, such as that by a fuel cell. However, it is not valid when only four calibrators are used on an infrared device. 


The are a lot of improvements to be made by the state in both their breath and blood alcohol laboratories. 

At the Ramsay Law Firm, we've hit on just a few that we've been able to find. But there's likely a lot more just beneath the surface. We've been functioning as an independent auditor for the state's crime lab. 

Here's a list of some of the major flaws that we've found:

Call Ramsay Law

The state crime lab won't reform on its own—that's why Ramsay Law serves as independent auditors—we take the science seriously.

We know the science inside and out, and we look at every aspect of your case to get the best possible outcome. 

Call us to discuss your case. Contact Ramsay Law at 651-604-0000. 

P.S. - Stay up to date by subscribing to our blog, where we explore the intersection of law and science around DWI cases.

Daniel Koewler