In order to be found guilty of DUI charges for alcohol intoxication in Tennessee based on your blood alcohol level, the prosecution must prove that you had a blood alcohol content of .08 or higher. In Tennessee, this proof comes from either breath or blood testing.
DUI convictions come with long-term serious consequences. Even if your BAC is .08 or greater on a breathalyzer machine, this doesn’t mean that you should plead guilty or accept the charges against you without a fight. There are several scenarios in which a skilled criminal defense attorney could argue that breath test results are inadmissible or unreliable.
1. Reliability: It may be possible to prove that a particular breathalyzer device isn’t reliable. Did you get several different breath test results on the same machine? Does the brand of machine used have any widely known reliability or maintenance issues? Defense attorneys in Boston, for example, recently got thousands of DUI cases dating back several years thrown out because they proved law enforcement agencies hadn’t performed regular maintenance to keep the machines properly functioning.
2. Calibration: Did someone well-trained in its operation properly calibrate the machine in question? Even with manufacturer-recommended routine maintenance, any results could be suspect without calibration. Think of it like this: to ensure accuracy, even the highest-quality scale needs “zeroing out” before weighing someone else.
3. Validity of the underlying stop: Did the officer have a reasonable suspicion of unlawful activity before stopping you? Were you speeding? Did you change lanes without signaling, run a stop sign or break a traffic law? If there was no valid reason for the stop, then it’s possible that any evidence obtained is inadmissible.
4. Improper training: Was the officer performing the breath test properly and sufficiently trained on its use? Did the officer observe you for the proper amount of time prior to the test? Though these machines may seem simple, they are actually complicated scientific devices that require skill to operate. Not properly cleaning, maintaining, calibrating or using them can all lead to erroneous results.
5. Testing officer not present to testify: Will the officer who performed the testing testify at your trial? Unless you are given an opportunity to confront the witnesses against you per the Sixth Amendment, a judge might find the evidence inadmissible.