Offices in Knoxville and Jacksboro, TN
Facebook Twitter LinkedIn

Call for a Free Consultation | We are Available 24/7

Call Us423-449-7980

We are Available 24/7

6 Things That Can Affect the Accuracy of DUI Breath Tests

Posted on in DUI/DWI

Knox County DUI defense lawyerIf you agreed to take a breathalyzer after getting stopped for DUI and the result was over 0.08%, you may feel as if your case is a lost cause. This is not true. Breath tests are far from perfect. Anything from improper storage to improperly trained officers could affect the results of a breathalyzer, causing your BAC to appear higher than it actually was. If you failed a breath test during a DUI arrest, you will need an experienced DUI lawyer to bring any potential challenges to your breath test results. 

What Problems Could Invalidate a DUI Breath Test in Tennessee? 

Breath tests are scientific equipment and must be treated as such. They are not like a kitchen appliance one can leave sitting in a cabinet and dust off every now and again. They require routine calibration and correct operation by a trained officer. The results of your breath test could be challenged if any of these circumstances were present: 

  • Improper operation - Depending on the specific type of machine used, there is a strict set of operating procedures that must be followed. An attorney will be able to evaluate whether there could have been an error in the way the test was used. 
  • Improper operator - In Tennessee, an officer must be specially certified to administer breath tests. An uncertified officer may make an error that interferes with the results. 
  • Calibration - To accurately detect BAC, the breathalyzer must have been correctly calibrated. Police departments should keep logs showing when their device was last calibrated. 
  • Observation - There is a mandatory 20-minute observation period during which the officer must watch you and make sure you do not eat, drink, or vomit before a breath test can be given. The reason for this is that residual alcohol in your mouth can artificially increase the results of a breath test. 
  • Radio waves - Cell phones and radios can interfere with the way a breathalyzer functions. Officers must be sure to keep these devices away from breath test machines. 
  • Unapproved devices - The breath testing device used must be one of those specifically approved in the state of Tennessee for this purpose. Approved devices must meet a series of standards that unapproved devices may not. 

If the prosecution is relying on the results of your breath test to convict you, you will need an attorney who is familiar with breath testing procedure to evaluate your case and raise any possible defenses. 

Contact a Knox County DUI Defense Attorney

If you were arrested for DUI and failed a breathalyzer, The Law Office of William F. Evans may still be able to challenge the results depending on the facts of your specific case. Our Knoxville DUI lawyers are experienced in building strong defenses for those charged with DUI. Call 423-449-7980 for a free consultation.



Lead Councel TACDL Elite Lawyer Top 40 Under 40 Tennessee Trial Lawyers Association National College of DUI Defense Member DWI Detection Certificate
Back to Top