How to Challenge the Results of a DWI Breath or Blood Test | Steven Wright Law


When a police officer believes that you are driving while intoxicated (DWI), they will ask you to submit to a blood or breath test to measure your blood alcohol content (BAC) or breath alcohol concentration (BrAC). In Texas, you can receive a DWI charge in three ways, but the most commonly known is if your BAC exceeds the legal limit of .08 percent. Steep penalties are on the table if they result in a conviction.

There are three standardized field sobriety tests (SFSTs) that law enforcement typically use before asking you to provide a sample. Even if your traffic stop progresses to breath or blood testing, numerous factors will trigger a false positive or erroneous result. Speak with a DWI attorney to help you defend your case if arrested as soon as possible.

3 Ways to Challenge a DWI Breath or Blood Test

Breath and blood tests are not perfect, and they are not always accurate. While blood tests can be more reliable than breath tests, this information does not imply that they are foolproof. Having an attorney that knows the science behind both of these methods will greatly help you find and challenge their results.

In addition to the numerous testing methods, these tests’ results can result in erroneous BAC measurements. As such, it is possible that you can receive a DWI charge and conviction due to testing errors. This opportunity gives you the chance to mount a defense regardless of the test results.

A few strategies that your DWI lawyer may use in your defense could include:

  1. Technical errors: Breath and blood tests can produce false results from a technical standpoint. Improper maintenance, inept handling, and application errors can cause the testing device to read incorrectly. A DWI lawyer understands how to investigate your case for technological errors.
  2. Procedural errors: When a sample it taken there are certain procedures that must be followed to ensure an accurate results. If the officer does not wait 15 minutes before administering a breath test, this could be grounds for having the result thrown out in court. If a blood sample does not have a proper chain of custody or was not refrigerated quick enough after it was taken, the results can be challenged as well. DWI laws are standardized uniformly throughout the United States. If the arresting officer makes ONE mistake, then his or her abilities come into question. From mishandling the sample to misreading the results, procedural errors are one way you can challenge a DWI breath or blood test. (This sounds too much like SFST language mixed with BAC I rewrote it)
  3. Illegal arrests: Even if it does not feel that way, you have rights when tested for a DWI in Texas. Law enforcement cannot violate your constitutionally protected rights, including illegal arrests for lack of probable cause, forced blood draws where a warrant was not obtained, or coercing you to give a sample when you don’t want to. Depending on the facts and circumstances, these actions can become your grounds for challenging your case. Always remember, you have the right to remain silent and you don’t have to consent to ANY testing!

There are countless ways that a mistake made by a police officer or an analyst that could impact the test results. There are so many other factors that many people don’t know about and only an experienced DWI attorney would know to look for. 

While the above-referenced list of defenses is possible, it is vital to recognize that no two DWI cases are alike. What may apply to your case may not apply to another when you legally consider the particulars of your situation. To determine if you can challenge your BAC results, speak with a DWI defense lawyer to represent your case in court.

Get In Touch with a Plano DWI Attorney

You should not have to assume responsibility for a crime that you did not commit. If you were accused of a DWI in Plano or Collin County (I would broden this out, but just a thought), contact Steven Wright Law for a Free Case Review at 214-441-6473 today or by completing the form below.

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