San Antonio DWI lawyer explains how a blood test can be challenged in court.

Blood tests for BAC are most often used in accidents where injuries have occurred. The blood test should be performed at the hospital by a trained EMT. Blood test regulations vary from state to state, therefore issues arising from improperly handled blood tests will vary as well. Well trained driving while intoxicated attorneys know that a blood test can be very easy to challenge.

Types of blood tests

Most commonly, a blood test for BAC will be performed on a whole blood sample. This can vary, though if the sample is taken at a hospital. Hospitals often use medical samples which test the blood serum rather than whole blood. Still in other cases, the blood sample is precipitated and then centrifuged to produce what is called “supernatant” to be analyzed. With these three different forms of testing, one can begin to see where discrepancies could arise.

Challenging blood tests

In a study entitled Distribution of Ethanol: Plasma to Whole Blood Ratios, Hodgson and Shajani, 18 Forensic Science journal 73 (1985), scientists set out to determine if there was a difference in outcomes of BAC among the three major types of blood tests. Their findings indicated that the serum test used by most hospitals showed BAC levels 11% higher than that of whole blood samples. The “supernatant” samples were 5% higher than whole blood. If you are facing a driving while intoxicated from a blood test, seek out a San Antonio driving while intoxicated attorney that understands these types of blood test discrepancies.

Your San Antonio driving while intoxicated attorney will also look at how your blood test was administered. Was the test performed by a qualified EMT? Did the EMT use alcohol to prep the area where blood was taken? Alcohol can affect the test results and therefore be grounds for suppressing the blood test results. Your driving while intoxicated attorney will also look at the chain of custody of the blood sample and determine if it was handled properly thereby assuring the sample was not possibly contaminated.

One other way that the test can be challenged is through the testimony of the expert who analyzed the sample. Standard methods of analysis must be followed carefully to ensure the results of the test are accurate. Without an expert to testify as the accuracy of the testing method and the proper administration of the testing method, the tests results may be inadmissible.

Get the help you need

If you are facing a driving while intoxicated conviction, seek help immediately. Do research, get the facts, and make an informed decision. A driving while intoxicated conviction can drastically alter your current standard of living. There is much that can be done to fight a driving while intoxicated . Find an experienced DWI defense lawyer who is able to aggressively fight for you. It is important to hire a lawyer experienced defending DWI cases. A DWI conviction can lead to license suspension, a criminal record, probation, hefty fines, increased insurance costs, and jail time. If you are facing a driving while intoxicated in or around San Antonio call our office for a free consultation at 210-224-8881.