Breath Test Machines Are Not Always Accurate

There are many issues with the breath test machine that can affect the validity of the test results. These issues often give a Defendant in a DWI case an advantage in trying to challenge a particular score. A lot of the issues that come up are very technical and require a certain base knowledge of the machine in order to present that challenge properly to a judge or a jury. Below you will find a quick discussion of a few of those issues.

First, the machine assumes that your body temperature is normal. If you have a fever, every degree of body temperature variation from normal will cause a change in the breath test result. That means that if you have a fever and you are blowing into a breath test machine you could blow an inaccurately high score.

Second, it assumes your “partition ratio” is 1:2100. This means that for every particle of alcohol in your lungs, it assumes there are 2100 particles in your blood. Human partition ratios can vary from 1:1500 to 1:3400. This simple assumption can lead to incredibly inaccurate scores.

Third, it assumes that your blood alcohol level has peaked and is decreasing. It generally takes 30 minutes on an empty stomach and 2 hours on a full stomach for your blood alcohol to peak. If you blow before you peak, then your breath alcohol level can be a higher score than your blood alcohol level, because breath alcohol comes from your arterial blood system and blood alcohol level is drawn from your veins. This also means that it may be a higher score than it was at the time you were driving.

These are but a few of the many potential issues with a breath test machine. There are many more behind the few selected here for a quick discussion. The simple fact is that not all breath test results are created equally, which is why it is always important to sit down with an experienced DWI attorney to discuss the specifics of your situation and accurately assess the strengths and weaknesses of your case.