Texas DWI Defense on Intoxilyzer 5000 Breath Alcohol Concentration

In our last blog entry, we discussed the variance on breath test results for the Intoxilyzer 5000 and how a breath test result of .089 should raise the question of reasonable doubt.

The results on breath alcohol concentration can be affected if there is any alcohol in the mouth. The guidelines require a fifteen (15) minute time period of observation to make sure the mouth is cleared of alcohol. In addition, alcohol in the stomach can get into the mouth if the person belches. That is why if at any time a person belches during the fifteen (15) minute period before giving a breath sample, the person must wait another fifteen minutes before giving a sample.


A strong San Antonio DWI lawyer defense tactic is to query the breath test operator as to whether he keeps a log sheet reflecting the beginning of the observation period and whether that time matches with the time listed on the records. Yet more often than not in Bexar county and surrounding counties, there is no real procedure to reflect when the observation period commences.

Many New Braunfels DWI attorneys will ask the breath test operator if they have video of the breath test and whether they have videotape of the required 15 minute observation period. More often than not, the video is missing. Jurors often question why there is no video of the breath test and the observation period if the prosecutor is relying so heavily on video of the traffic stop . There is a question then as to whether the breath test operator complied with the mandatory 15 minute observation period.

Besides a 15 minute observation period, the breath test operator must verify the temperature of a test sample of fluid. The purpose behind a test of the temperature is to simulate a person’s lung. When alcohol evaporates from the blood, it collects in the lungs and leaves the lungs when a person exhales.

The breath test supervisor mixes water and alcohol in a container and pumps evaporated water from the jar into the Intoxilyzer 5000. If the water and alcohol is properly mixed, the test sample will read .08 .The test sample fluid and the evaporated water should be at a certain temperature because a person’s temperature can affect breath test results. A temperature higher than 98.5 degrees will create a higher result. The temperature of the test sample must be at 98.5. A technician uses an old-fashioned mercury thermometer to test the temperature of the test sample. In an age of digital thermometers, many jurors will question whether a mercury thermometer is enough of a precise instrument.

More often than not, neither the breath test operator nor the technical supervisor employ a log sheet to record the temperature of the test sample at the time the person is blowing into the Intoxylizer. Again, this omission can be exploited by a skilled Atascosa criminal defense lawyer .

Contact Information