Medical conditions that can be problematic to a prosecutor in obtaining a DWI conviction include acid-reflux, GERD, and heartburn which can cause a sample from a breath test to be affected. These conditions, properly documented by a physician could provide you with a defense that stops a conviction. That said, you will find that a good dallas dwi lawyer would not let you base your case on such challenges unless the BAC was extremely close to the legal limit, or other circumstances made this a highly likely success.
Another defense relies upon a claim regarding tests not being valid. Guidelines have been established for SFST’s (Field Sobriety Tests,) consisting of 3 tests, that range from HGN (Horizontal Gaze Nystagmus), WAT (Walk & Turn, as well as standing on one leg. the “OLS” or One-Leg Stand. Other tests performed in the field that are performed or used by a police officer could be invalidated when challenged.
Challenge to the results from the breathalyzer. Breathalyzer units require proper care and trained use for them to operate properly and give results that are accurate. Even when used correctly, the results can be unreliable. The portable devices are especially susceptible to failure. The equipment needs to be tested and calibrated according to the standards and instructions provided by the device manufacturer.
Often, several departments could be making use of outdated breathalyzer equipment and replacement parts that are out of use make it even more difficult to keep up with the maintenance, testing, and care for such units. Once these machines become outdated, they are unreliable and unstable. They should certainly be challenged for accuracy, admissibility, and more.
For a person to have a good challenge to such breathalyzer results, she or he will required expert dwi offense testimony about the unreliability in specific situations where these older models are used. The police officer must testify about the calibration, and if they state that they did calibrate the machine, but the calibration was not recorded, the procedural error could result in winning your case. If police did not adhere to procedures that were deemed required in the administration of the breathalyzer test, this would indicate an additional potential “out” for your case. By establishing reasonable doubt in the minds of the jurors regarding the accuracy and reliability of the results from this breathalyzer, a not guilty verdict is possible.
One final note is regarding a challenge to the actual blood work that showed a BAC over the legal limit for operating a motor vehicle in your state. Texas blood alcohol content tests must adhere to very specific guidelines, procedures, and rules that are governed by statute. If police or hospital staff fail in their following such procedure, admissibility can be challenged with regards to the BAC results.