Other Temperature Issues with Intoxilyzer 5000 in DWI Defense

In our last blog entry we discussed mistakes breath test operators make during the administration of a DWI breath test . In this blog entry we will discuss other temperature issues involved with the Intoxylizer which a San Antonio DWI lawyer can exploit to create reasonable doubt.

The basic premise of the Intoxylizer is that its results are based on the average temperature of a person – 98.5 degrees Fahrenheit. Yet many people’s average temperature vary by a few degrees higher or lower than this number. So theoretically, if the driver’s core base temperature is greater than 98.5 degrees Fahrenheit, then the Intoxilyzer will yield a test result that is greater than the true measure of the breath alcohol concentration (BrAC). More often than not, the operators do not take the driver’s initial temperature and record it so they can make adjustments off the test results.

In fact, if the case is a Bexar County DWI matter and the breath result was taken in the San Antonio Magistrate’s office, there would be a medical professional present at all times who can take the driver’s temperature and it would not be difficult.


Another important factor is the tube where the driver blows into the chamber. Many jurors do not know that the tube itself is heated and temperature has to be calibrated. A heated tube can impact the breath sample temperature and consequently the BrAC. The reality is that the technical supervisor for the Intoxilyzer cannot say if the tube temperature was in proper order when the driver blew into the tube. The tube could theoretically be at a higher or lower temperature than recommended.

In addition, there are temperature issues a Comal County DWI defense lawyer can also point out with the chamber. Sometimes, a technical supervisor will argue that the test sample temperature is not significant due to the chamber temperature. This is faulty reasoning because it is a requirement that the test sample temperature be monitored prior to starting the breath test. There would be no requirement to monitor the temperature of the test sample if the heat of the chamber cancelled out the driver’s core body temperature.

As noted above, temperature can be a major factor in the ability to challenge the Intoxilyzer results and obtain a favorable DWI defense.

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