Plano DWI Tests

In Texas, a driver will be arrested for Driving While Intoxicated (DWI) if they are found to have a Blood Alcohol Content (BAC) of .08% or greater. DWI charges can lead to harsh penalties and costly fines. Whether you are currently facing charges associated with DWI or have general questions associated with DWI, it is in your best interest to educate yourself on the laws in Texas. Call an experienced Plano DWI lawyer to schedule a consultation about your case.


If you are suspected of driving under the influence, a law enforcement officer has the right to stop you and ask questions. They can also request that you perform a variety of tests in order to determine whether you are driving while intoxicated.

Initially, the officer may have a simple conversation with you to get an idea if you have been drinking. This is typically when the officer will request to see your license, proof of insurance, and registration. The officer can often easily observe indicators of impairment through noticing an alcohol odor or slurred speech.


If the officer determines that you have been consuming alcohol, he will ask you to exit the vehicle in order to have you participate in one or more field sobriety tests.

There are three main tests that are used by Texas law enforcement and others nationwide:

  • Horizontal gaze nystagmus (HGN): The officer will observe the jerking that occurs when your eyes move from side-to-side. There is always some level of jerking with any individual – sober or not – but if you have been consuming alcohol, the jerking will be much more apparent.
  • One-Leg stand: The officer will request that the driver stand with one foot approximately six inches off the ground while counting out loud for approximately 30 seconds. This test lets the officer observe whether the individual can maintain balance while performing a basic mental task at the same time.
  • Walk and turn: This method requires the driver to walk in a straight line for nine steps, make a turn, and repeat the process in the opposite direction. Again, this test is used to evaluate the individual’s balance and mental bcapability while performing a simple task.


If the officer believes that the driver is under the influence of alcohol, he may then decide to perform a breath or other chemical test in order to obtain an official BAC.

These tests include:

  • Breath test: The officer will use a breathalyzer-type device to evaluate one’s BAC. This device can be used at the scene by simply taking a sample of the driver’s breath to determine the BAC.
  • Blood test: Medical personnel will test the driver’s blood to evaluate the BAC. While this method is more invasive and less convenient than a breath test, it may be the most appropriate means for the situation (i.e., the driver is unconscious). After the sample is obtained, it will be sent to a lab that will conclude the driver’s BAC.
  • Urine test: This test is administered by a medically trained individual and the sample will be tested by a lab. This is arguably the most invasive means of determining one’s BAC and is therefore used least often.

If you have been arrested and charged with DWI based on evidence gathered from field sobriety tests and/or chemical testing, you have options. Contact an experienced Plano DWI attorney who will listen to the facts of your specific case and ensure that your rights are protected in court.

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Notification of all Court settings and updates in writing, as well as assistance preparing for your DWI court appearance.
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