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For Texas DWIs: Can I Choose Between a Breath or Blood Test?

When a Texas police officer has probable cause to believe you have driven a vehicle while intoxicated, Texas implied consent law calls for a blood or breath test to be administered. And when the officer suspects drinking and driving, it is up to the sole discretion of the arresting officer to decide whether or not a blood or breath test is administered.

Implied Consent Laws in Texas

Driving is a privilege, not a right. By driving on Texas roads, you commit to following the rules and regulations put in place by the State of Texas. One rule is your implied consent to take a blood or breath test if arrested for suspicion of DWI.

While you can withdraw your consent and refuse to take a breath or blood test, there can be additional legal consequences you could face for doing so. There are also circumstances where it is mandatory for law enforcement to take a blood sample from you. If you are unconscious or otherwise unable to withdraw your consent, a law enforcement officer can rely on your implied consent to draw your blood.

The Arresting Officer Chooses a Breath or Blood Test

Under Texas law, it is the arresting officer's decision on whether to request a breath or blood sample. According to the Texas Transportation Code, if a peace officer has reasonable grounds to believe you are driving while intoxicated: "One or more specimens of a person's breath or blood may be taken if the person is arrested."

Once the police officer selects the type of test requested, you have the opportunity to submit to the request or refuse. It is the officer's duty to inform you that you have the right to refuse to submit to a chemical test as well as the consequences for making such a refusal. If you agree to a blood or breath test, the peace officer is required to administer the test as soon as possible.

Mandatory Testing

While you do have the right to refuse a chemical test, there is one situation in which a peace officer can take a sample from you against your will. In cases where a driver refuses to take a chemical test in Texas, it is possible that the arresting officer will seek a warrant for a blood draw.

  • If, after the officer presents an affidavit outlining on what his suspicions are based, and a judge issues a warrant for a blood draw, there is nothing you can do to stop it.
  • If a Texas law enforcement officer takes a blood or breath specimen from you without a warrant or without your consent, your Texas DWI attorney will have grounds to have the results of that test excluded from your DWI trial.

Your Right to a Second Independent Blood Test

Most people do not know—because police officers do not inform them—that if you consent to a blood or breath test, you have the right to have your own independent blood sample taken and tested by a healthcare professional of your choice, pursuant to Texas Transportation Code Section 724.09:

A person who submits to the taking of a specimen of breath, blood, urine, or another bodily substance at the request or order of a peace officer may, on request and within a reasonable time not to exceed two hours after the arrest, have a physician, qualified technician, chemist, or registered professional nurse selected by the person take for analysis an additional specimen of the person's blood.

Police officers are required to give you a reasonable opportunity to contact a medical professional to take an additional blood sample. It's important to note that this is only for blood samples; you do not have the right to request additional breath testing, ostensibly because no medical professional trusts a breath sample for accuracy or reliability. While the officers at the jail must provide you with an opportunity to obtain a second sample, they are under no obligation to transport you to a medical facility.

Consequences of Refusing to Submit

If you refuse to submit to a blood or breath test, your driver's license can be suspended for a minimum of 180 days. That becomes a two-year suspension if you have had any "alcohol or drug-related enforcement actions" within the last 10 years.

An enforcement action includes:

Should I Choose Blood or Breathe Tests?

Both forms of testing have their own accuracy issues. While blood tests are typically more accurate, there are factors that can render either test entirely inaccurate. A thorough investigation of the collection and testing of your specimen by your attorney may lead to conclusive evidence that the results were tainted and should be excluded from your trial.

Blood Testing Issues

While blood test results are typically more accurate than breath tests, that doesn't mean faulty results and false positives aren't possible. Contaminated specimens can lead to false positives, and improper handling can lead to your specimen being confused with that of another person. The most common problems with blood testing are errors in the collection or storage of the blood, as well as breaks in the chain of custody.

Collection and Storage of your Specimen

There are a number of ways in which faulty collection or storage practices can lead to a BAC result that should not be relied on. For instance, samples that are taken hours after an arrest are a common problem. As time goes on, your BAC will rise or fall depending on when your last drink was. If law enforcement waits to take a sample, it's likely that your BAC at the time of testing will be much higher than when you were driving.

Also, improperly taking or storing the blood specimen can ruin the integrity of the sample. Errors in drawing the blood sample can taint the entire specimen. The risk of a tainted sample is even higher if blood samples are not stored properly. Certain chemicals are added to a blood sample to prevent it from fermenting. Fermentation actually creates alcohol, meaning improperly storing your blood sample may leave you with a false positive on your test.

Chain of Custody

Your blood test must be analyzed in a laboratory setting. Because of that, it is inevitable that your sample will go through many hands during the testing process. The state must account for every person who handles your blood sample. If it cannot account for a link in the chain of custody of your sample, your DWI defense attorney may be able to have the results of your blood test excluded from your trial.

Breath Testing Issues

While there are a few issues that can come up with blood tests, the potential problems with breath tests are much more expansive. The results of your breath test can be affected by improperly calibrated machines, tests conducted by improperly trained individuals, or even false positives from food you have recently eaten.

The results from an improperly calibrated breathalyzer machine aren't worth the paper they're printed on. These sensitive machines only provide accurate readings if they are carefully maintained, and failing to do so renders the results worthless.

Even if a breathalyzer is calibrated properly, the results can be skewed if the operator makes an error during testing. Peace officers are required to be trained and certified before they can operate these machines, but over time, these officers may forget their training. If the officer who takes your breathalyzer test wasn't properly certified to do so, your defense attorney may be able to have the results of those tests excluded.

Finally, there are many circumstances that can lead to false positives. Food is a big example. In fact, there is a long list of foods that can lead to false positives in BAC testing, including:

  • Very ripe fruit
  • Yeast breads
  • Protein bars
  • Honey Buns
  • Hot sauce
  • Vanilla extract
  • Kombucha
  • Vinegar
  • Lip balm
  • Energy drinks
  • Sugarfree gum

There are other issues that can lead to inaccurate breath test results as well. Medical conditions, including diabetes, asthma, and acid reflux, can cause a breath test to report a false positive result. Unusual breathing patterns, insufficient breath samples, and shallow breathing may also result in a sample showing alcohol when you haven't been drinking.

Contact Our Harris County DWI Lawyer for Breath and Blood Tests

If you submitted to a blood or breath test after an arrest for a DWI in Texas, attorney Doug Murphy may be able to challenge the results of that test. The Doug Murphy Law Firm, P.C. will thoroughly investigate every aspect of your blood or breath sample. If the State of Texas failed to follow the appropriate procedures in collecting, storing, or testing the sample, Doug Murphy will fight to have those test results barred from your trial.

Doug Murphy relies on his experience and training to give his clients the best DWI defense possible. Doug Murphy is one of only two attorneys in the State of Texas to be Board Certified in both DWI and criminal defense. He is ready to put his experience to work for you. Contact the Doug Murphy Law Firm, P.C. today at 713-229-8333 for a free consultation.

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