Trusting the black box

In many places, we encounter what is sometimes referred to as “black box” technology. This type of technology has become more and more commonplace, and with it, the need to trust without really understanding.

Take an automobile. At one time, the basics of engine technology were so straightforward that any backyard mechanic could work on a vehicle and keep it running. Now, with vast numbers of computerized controls, even simple repairs may require sophisticated electronic diagnostic equipment. Drivers just have to trust that it will run, and when it doesn’t, call for a specialist.

This lack of understanding can be a problem in other areas. Breath testing devices are like magic boxes. A suspected drunk driver blows into a mouthpiece and a short time later, a number appears on the screen. It tells the operator that the suspect’s blood alcohol content is a certain number.

But is it correct? A group of Tennessee DUI lawyers and defendants are taking a case involving how we know the answer to that question to the Tennessee court of appeals. The case over how the Intoxilyzer EC/IR II is calibrated.

There are 132 police and law enforcement agencies that use this model in Tennessee, but they are all calibrated by the Tennessee Bureau of Investigation. During the 2005 to 2013 period, the TBI only calibrated the devices at a BAC of 0.082, slightly over the state’s legal limit of 0.08.

The problem with that is that it is less accurate than calibration done at three points. In addition, there were no written policies at the TBI governing calibration of the breath testing devices. The agency claims they had “policies,” but if nothing is written down, it would be hard to know what they were and if they were being followed properly.

The agency has since created written policies for this issue, but the public’s trust of this kind of black box technology is undermined when the responsible agency seems to have had such loose standards governing the accuracy of these devices.

Source:, “Group of lawyers, defendants claim commonly-used breathalyzer is inaccurate,” Alanna Autler, May 6, 2015

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