Accuracy in Fort Worth Breathalyzer Tests

Breathalyzer tests are highly inaccurate. They might by accident get close to the right value, but more often than not, they are completely wrong. Results are usually much higher than what the person’s true alcohol level is. In fact, if two people with the same 0.08 alcohol level in their blood are tested on the same machine, each could test as low as 0.02 and as high as 0.14, because of the differences in their physiology. One of the problems with breath testing is the fact that different people get different amounts of alcohol in their breath from the same amount of alcohol in their blood.

Breath testing is not an accurate way whatsoever to estimate what a person’s true blood alcohol level is. This is very important because it’s the alcohol in the blood that affects somebody, not the alcohol in his or her breath. Further, the breath test machine takes two samples from the same person. So a person blows into the machine and says they get the result of 0.08. Well, the operator who is giving this test to the person is supposed to wait a few minutes or supposed to blow a little bit of air through the machine to maybe get what alcohol is there, and then they take a second test from the same person. Now that second test can be as high as 0.10 or as low as 0.06, and the government says that that’s reliable and that’s an admissible test.

What Does a Breathalyzer Look For?

The breath test machine allows for, plus or minus, 0.02 or difference of as much as 0.04 from between what the second result can be from the first test, which is incredible. If you look at a 0.08 test and the next test can be as low as 0.06 or as high as 0.10, that’s plus or minus 25 percent. That’s how different those two samples can be, and they will still say that’s admissible. Most people don’t think that’s accurate enough to rely on, so it’s really not an accurate test at all. Furthermore, the machine has a reference sample in it that’s been prepared to be 0.08. This reference sample is maintained in the machine, and every time the machine takes somebody’s breath test, it measures the reference sample, which is supposed to be a known value of 0.08. The machine can read that reference sample as low as 0.07 or as high as 0.09, and that’s still admissible.

This means that the machine can be up to 12 percent off, just in reading a known sample. When you combine how far off the machine can be in reading its own sample, and then how far off it can be in reading two samples from an individual, you can see how that breath test is just not reliable at all. This is something that we can show the jury.

How Breathalyzer Errors Occur

The machine can read many things and conclude that there is alcohol present, even if this is untrue. People who might be exposed to chemicals in their work or in their hobbies, such as paints, thinners, and solvents can be absorbed into the system, and come out in a person’s breath and be read as alcohol. The machine may be reading something that it thinks is alcohol that’s not alcohol at all, or that might combine with some alcohol that’s present in the person and raise the value higher than it should be. So there are many things that can contaminate the sample that may be in the person’s body.

There are also problems with medical conditions, such as people who are diabetic or people who are in a condition called ketoacidosis, or people who are having a blood sugar emergency. This can cause levels of ketones in the body to rise to a higher level, and the machine can read the ketones and thinks that those things are alcohol. Again, because the machine reads that as alcohol, it can raise the level of alcohol it detects, or read a false positive.

There are also things that might be in the environment, such as exhaust from cars or other machines. Radio Frequency Interference (RFI) can interfere with the machine, and that is all over the place, especially in a police department. There are antennas everywhere, door openers and things like that, all kinds of things can create RFI that can affect or cause the test to be higher than it should be, or otherwise make it unreliable. In fact, cell phones work at all kinds of frequencies much greater than what they did 20 or 30 years ago, and these machines have not been tested to show that they are not affected by the RFI generated by cell phones. An officer may have a cell phone right there sitting by him and even when that thing is not on, cell phones can be generating RFI, which may affect the test. There are all kinds of things that can make this test unreliable, and that’s what we can show the jury.


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(682) 204-4066 No podemos recibir imágenes por mensaje de texto, así que envíelas por correo electrónico o entréguelas personalmente en nuestra oficina.


(682) 204-4066 We cannot receive pictures via text so please send those via email or hand deliver to our office.

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