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What specific drugs are tested for in a blood sample drawn in a DWI case?

Houston, TX |

Arrested for DWI in July 09. Took a field breathalyzer (0.04) then another at the station(0.028) Then taken to another station to have blood drawn. Am now concerned that my prescription meds will be a problem.

Attorney Answers 2


Based on what you have written, it is not overly apparent what you are seeking. You should consult with a law firm in the Houston area who handles DWI cases. The local law firm can assist you with protecting your rights and interests. If my local law firm can assist you with this legal issue or any other legal matter, please contact us at to arrange for an initial consultation. The above response given is not intended to create, nor does it create an on-going duty to respond to questions. Additionally, the response does not form an attorney-client relationship, nor is it intended to be anything other than an educated opinion. It should not be relied upon as legal advice. The response given is based upon the limited facts provided by the person asking the question. To the extent additional or different facts exist, the response might possibly change.

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Short answer, they can test for whatever they want, but they will surely be testing for alcohol. The 0.04 you blew in the field was on a Portable Breath Tester (PBT) and the result is inadmissible in court, if we want it to be inadmissible. The breath test you took at the station was on an Intoxilyzer 5000EN. This is the breath test that the State of Texas has deemed scientifically reliable and it's up to the State to satisfy the Kelly prongs and get it admitted.

However, what concerns me is that both of your tests were below a 0.08. That means you were not intoxicated on alcohol. What they are going to come after you now is that you were intoxicated on prescription meds, or meds combined with the alcohol which caused a synergistic effect. See a case styled Layton v State of Texas in 2009.

In order for the State to prove up the meds they are going to need to know when you took those meds, what dosage, what the half-life is, and an expert to testify to the effects of this medication with those known values.

They will need a Drug Recognition Expert (DRE) to testify about the effects of your medication. So even if your meds show up in the blood, they still need an expert to testify how what showed up was affecting you. This is not easy. An expert can't just come in and compare you to the average person. If they can't make it relevant to you and probative, then the blood test should be suppressed. (this depends greatly on the Judge). They should have had a DRE run a drug recogniton evaluation on you, which would have included: measuring your pulse rate, pupil size, the SFSTs at the station, muscle rigidity, signs of injestion, admissions, etc. It's a very technical 14 step process. There are very few agencies and officers that can get this correct.

In the end, you have a very defendable case, assuming the video doesn't show a gross loss of physical and mental faculties due to intoxication. Contact a lawyer who knows about DRE and DWIs. Prescription meds and blood truly is the next wave of science that we are conquering. Please feel free to contact me for a more thorough complimentary consultation.

God Bless America,
Mark Thiessen

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