In order to prove an OWI case, the prosecution often relies on the blood alcohol content (BAC) reading as evidence. If a driver does not cooperate by taking the breathalyzer test, the police may try to strengthen the case by asking a judge to sign a search warrant for a blood test. This is especially true in OWI accident cases involving serious injuries and/or death.
If all the conditions are proper and appropriate, the testing can be very accurate. The problem potentially with breath testing, for example, is that the machine itself has some limitations with regard to its ability to properly perceive exclusively alcohol.
Challenging the Blood TestThe first thing an OWI defense lawyer will do if a client was subjected to a court-ordered blood test is conduct an investigation to determine the validity of the search warrant. For example, if the blood test was administered before the officer had a physical copy of the search warrant, an attorney may argue that it was invalid.
Even if the blood test search warrant is deemed valid, there are several ways to challenge the test. Blood tests must follow a very specific chain of command—if any part of that chain is missing, the results of the test could be thrown out. Improperly administered blood tests can also falsely inflate the BAC reading. Additionally, there can be a multitude of issues or potential problems, contamination that can occur during the draw of the blood from the person's arm. If that blood gets contaminated, that also can cause a false result.
There are other substances that can be on human breath, like acetone, that can cause an interference with the machine and be misread as alcohol. That's one problem with breath testing as it relates to the machine itself. There are a variety of potential problems as it relates to the persons who're being tested–so the driver's breath.
So, for example, if the driver has an issue with their respiratory system or their digestive system, both of those can potentially have an impact on the result and again cause falsely high results. So a common potential problem with breath testing is if the person has an advanced state of heartburn, what we call GERD–GERD standing for Gastroesophageal Reflux Disease.
If the person has that condition than what can happen is the raw alcohol–as well as the alcohol vapors–can erupt from the stomach into the mouth and as the person's blowing into the machine, the machine can't distinguish the mouth alcohol from the breath alcohol; again causing the machine to report a falsely high result. Learn how we contest a blood test here.
Determining Blood ContaminationWell, the first thing in the instance of a blood test, the first thing to look for is to determine whether or not the client's explanation of the drinking pattern makes sense as it pertains to their behavior at the roadside as well as the test result itself.
For example, if a client comes into the office, and they say that they had three drinks of alcohol, and we look at the video tape and we can see that the person looks very sober, and yet the blood test result is, let's just say a 1.7, we would say there is something wrong with that blood test and we would want to figure out what that thing is.
In order to make that determination, a request to the state lab would be made for the documents and things–what they call the case file–that would include all of the chromatographs and all of the documentation that they keep establishing that the machine is working properly.
We can look at those chromatographs, the actual raw data, and see if there is a problem. That can tell us in and of itself that there may be a problem. We're also looking for problems in the chain of evidence or problems with the conditions under which the blood was drawn. Again, any of which can have an impact on the end result.