DUI Blood Test

A conviction for driving under the influence (DUI) of alcohol or drugs generally requires evidence of the crime beyond a reasonable doubt. In many DUI cases, blood tests are used to show that the amount of drugs or alcohol in the driver’s body was above the legal limit. If you are facing charges for driving while under the influence, you can protect your rights and seek guidance from a Nashville DUI lawyer. Bernie McEvoy serves residents throughout Davidson and Williamson Counties and can help you seek to defend against DUI blood test evidence in your case.

In Tennessee, it is illegal for a person to operate a vehicle while under the influence of alcohol, drugs, or a combination of both alcohol and drugs. A law enforcement officer with probable cause to believe that a driver is intoxicated or drugged may ask the driver to take a breath or blood test, or both, in order to determine the drug and/or alcohol content of their blood. A DUI blood test is generally more intrusive than a breath test. While a breath test simply requires the driver to blow into the testing machine, a blood test requires a qualified medical professional to collect a test sample by drawing blood from the driver. The blood sample is then forwarded to an accredited crime laboratory for a toxicology examination. If the test results indicate that the driver had an unlawful amount of alcohol or drugs in their system, they may be used to support a DUI charge against the driver. The test results also may be presented as evidence against the defendant at trial.

In most cases, DUI blood testing can provide more information about a person than a breath sample, and the results are typically more accurate. Blood testing may be particularly important in a drug DUI case, because it can identify the type of controlled substance in a person’s system, as well as the amount. However, under Tennessee law, a blood test may only be administered when certain conditions are met. Primarily, the law enforcement officer must have probable cause to believe the person was driving under the influence of alcohol or drugs, or committed a related DUI offense. In addition, one of the following must apply:

• The driver signs a standardized waiver;
• The driver consents to blood testing;
• The police officer obtains a search warrant authorizing a blood test;
• There are exigent circumstances allowing an exception to the search warrant requirement.

If the driver refuses or obstructs a blood test that is authorized by a valid warrant, the driver may be charged with a misdemeanor criminal offense.

Presenting an effective defense to a DUI charge will depend on the facts of the specific case, and a skilled DUI attorney can assist you in preparing an appropriate defense in your situation. In some cases, the court may have reason to exclude the results of a DUI blood test from trial. For example, prosecutorial or police misconduct, an invalid warrant, or a violation of the driver’s constitutional rights may affect the admissibility of the blood test results. If the blood sample was not taken by an authorized person, or if the chain of custody cannot be traced, the defense may move to suppress the evidence. In cases where the blood test results are admitted into evidence, the defense may retain an independent lab to perform additional blood testing, or an expert to testify as to any circumstances that may have produced inaccurate results.

Attorney Bernie McEvoy can provide guidance regarding DUI blood tests, and help drivers defend against any related charges that may arise. He can represent defendants against drunk and drugged driving charges in Nashville, Franklin, and many other cities in Davidson and Williamson Counties. Schedule a free consultation by calling our office at (615) 255-9595 during business hours or (615) 804-8779 on evenings and weekends, or contacting us online.