The testing of a driver’s blood for blood alcohol content in Mississippi DUI crimes is becoming more common, and is considered more accurate than breath testing. But because it is such a complex, exact science, blood testing has its own problems which can lead to an invalid test result (which can be good news for the accused). To see if your case has any such problems, talk to an Olive Branch DUI lawyer today.

Call Stegall Law Firm at 901-205-9894 for more information

At the heart of DUI blood analysis is something called chromotography. Chromotography is the process of seperation. A chromatogram (the machine) will analyze the suspect’s blood for levels of alcohol or drugs. The blood itself is not analyzed, but instead the gaseous portion above the blood. As the gas is moved through the machine in the analysis phase, certain parts will be removed and “stick” to the inside walls. That’s seperation.

But it has to be done exactly right. Scientific theories state that at equilibrium, in a closed system, at a static temperature, pressure, and air flow, the amount in the gas portion will be proportionate to that in the liquid portion (the blood). That means if there are any changes in pressure, temperature, or flow rate, or there are any leaks, then the result is no longer valid.

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    So many things have to go exactly right in order to get an accurate blood reading. The blood has to be drawn, transported, and stored properly. At the lab, the blood must be heated to the correct temperature in order to get volatile compounds into the head space gas above the liquid. There then has to be an equilibrium of the ratio of volatile compounds in the liquid to the volatile compounds in the head-space before the head-space gas is sampled.

    In order to tell how much alcohol is in the sample, the machine has to first accurately separate it out. Without that, you’ll never be able to tell how much. And the way the machine tells you that is through its chromatogram, which is basically the printed report showing the results of the separation. If that report does not show equal, accurate seperation of alcohol from other molecules in the sample, we’ll never know how much was actually in there. And that is how reasonable doubt is created. If the state can’t prove how much alcohol was in a driver’s system, how can it prove she was under the influence?

    Patrick Stegall is an Olive Branch DUI lawyer. He examines DUI blood and breath cases for weaknesses and inconsistencies in an effort to prove his clients’ innocence. If you’ve been charged with drunk driving in Mississippi, contact Mr. Stegall so he can review your case. Call him at (901) 205-9894 or email him at

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