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National Association of Criminal Defense Lawyers
Tennessee Bar Association
National College of DUI Defense
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DUI: Breath and Blood Tests

If you are pulled over based on a suspicion of driving under the influence, the officer may ask you to submit to a breath test or a blood test. The breath test will be administered via a breathalyzer and if an individual blows a BAC that exceeds the legal limits enforced by the state (0.08 percent in Tennessee for adults 21 years and older), then he or she may be subjected to further tests and arrested. Blowing over the legal limit does not necessarily lead to an automatic conviction, because there are multiple avenues by which your defense attorney can attack the validity of the test.

What are Common Sources of Breathalyzer Error?

Breathalyzers, like all machines, are susceptible to error. Your attorney may be able to base your defense on one or more of the following common sources of breathalyzer error:

  • Calibration: The sensors in breathalyzers are prone to contamination and interference from various substances. Due to this, sensors require periodic recalibration, or else, the machine's results may be inaccurate. If your arresting officer administered a test with an improperly calibrated breathalyzer, you may have the results thrown out.
  • Mouth Alcohol: Mouthwash and gum can inflate BAC results. Dentures may also inadvertently retain alcohol inside the mouth, leading to an inaccurate reading.
  • Absorptive Phase: The body takes anywhere from 45 minutes to two hours to absorb alcohol and the absorption of alcohol is not evenly distributed throughout the whole body. The lungs can absorb alcohol more quickly than other parts of the body, leading to inflated BAC test results.
Blood Tests

Alternatively, an officer may ask you to submit to a blood test. Once a blood sample is obtained, the lab may test for both alcohol and drugs if the officer or the district attorney requests it. While breath tests are typically administered at the jail in Davidson County, blood tests must be administered by a qualified practitioner and you have the right to request which hospital you want to be taken to within the county.

If you do not consent to the breath or blood test you will be charged with violating the implied consent law and the officer will have to obtain a warrant. However, a warrant is not required for a breath or blood test if there is probable cause the driver was driving under the influence and one of three scenarios exist: (1) the driver was involved in an accident that resulted in death or injury of another person; (2) the driver had a child under the age of 18 in the vehicle; or (3) the driver has a prior DUI, vehicular assault, aggravated vehicular assault, or vehicular homicide conviction.

What Happens if I Refuse a Breathalyzer or Blood Test in Tennessee?

In Tennessee, by virtue of operating a motor vehicle you are deemed to have provided implied consent to chemical testing (breathe, blood, urine) at the request of a police officer. If you are pulled over on suspicion of DUI and asked to submit to a breathalyzer, blood test, or urine test and you refuse then you will be charged with violating the implied consent law. This will result in a minimum one year suspension of your license and, depending on your criminal history, you may have to install an ignition interlock device at your own expense. 

Contact Baker Associates

If you have been charged with a DUI or issued a citation for violating the implied consent law, it is absolutely vital that you get in touch with a dependable Tennessee defense attorney right away. Our extensive knowledge and resources allow us to employ the best legal strategies in court for our clients.

If you wish to learn more about how we can help you, please call us today at (615) 622-0595.