Houston DWIs and Blood Drug Toxicology

Posted by Doug Murphy | Sep 14, 2021 | 0 Comments

If you're facing a drug DWI, you may be frightened and unsure of what happens next. In Texas, you can be arrested for driving while intoxicated if you:

  • Operate a vehicle in a public place, and
  • You don't have the normal use of your mental or physical faculties, or
  • You have a blood alcohol concentration of .08% or more.

So, you can still face a DWI if you don't have the normal use of your mental or physical faculties due to alcohol, a controlled substance, an illegal drug, or a combination of these.

Drug DWI

Proving a DWI due to drug use is a bit more complicated than an alcohol-related DWI. There is no single blood or breath test the police can conduct like with alcohol intoxication. Instead, the police use something called the Drug Recognition Expert (DRE) Protocol. The DRE protocol involves 12 steps, most of which are highly subjective and observational, conducted by the police to determine whether a driver is impaired by substances other than alcohol. The final step of the 12 is a toxicological examination.

Drug Toxicology Testing

You may face a conviction for an alcohol DWI in Texas if a blood test reveals a BAC of .08% or higher. However, under Texas law, there is no objective standard or level of a controlled substance that results in impairment or intoxication. As a result, a prosecutor may try to use a positive test for a controlled or illegal substance as evidence of a DWI. But a positive drug test is not the same as a BAC test for alcohol.

Moreover, blood tests are still subject to errors because of inadequate testing or training. Testing errors can result from:

  • Using improperly calibrated equipment,
  • Using outdated testing kits,
  • Sample contamination,
  • Improperly storing samples,
  • Tests administered by an improperly or inadequately trained person,
  • Test administration errors,
  • Lab errors,
  • Pre-existing medical conditions that can affect equipment or lab readings,
  • Failing to follow accredited forensic lab practices,
  • Failing to follow lab validation methods and operating guidelines,
  • Breaking the chain of custody for samples,
  • “Dry labbing,” where the lab provides the results but fails to conduct a complete analysis.

Even if blood toxicology results show that you had controlled or illegal substances in your blood at the time of your blood test, a skilled DWI attorney can still defend you from a DWI charge.

Hire an Experienced Controlled Substance DWI and Criminal Defense Attorney

If you're facing a controlled substance DWI, please don't forget that you are innocent until proven guilty. Just because the police charge you with a controlled substance DWI, even with a positive toxicology test for drugs, does not mean a court will find you guilty. CoA controlled substance DWI can be more complicated than a typical DWI case, requiring an attorney with substantive experience in complex controlled substance DWI cases. You will need a skilled criminal defense attorney with extensive knowledge about DRE protocols and training and how the police conduct toxicology tests.

Attorney Doug Murphy is Board Certified in both DWI Defense and Criminal Defense Law. He is one of only two Texas attorneys Board Certified in both of these legal specialties and has handled hundreds of the most complex DWI cases, including controlled substance DWIs.

Moreover, U.S. News and World Report recently named Doug Murphy as a Best Lawyer in America in Houston for DWI defense in 2021. There's a reason the Houston Press calls him the “Drinking Driver's Best Friend.” Contact Doug today online or at 713-229-8333 to schedule your consultation.

About the Author

Doug Murphy

Doug Murphy is one of only two Texas lawyers Board Certified in Criminal Law by the Texas Board of Legal Specialization, and also in DWI Defense by the National College for DUI Defense, accredited by the American Bar Association and the Texas Board of Legal Specialization.


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