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What Evidence Can Prosecutors Use to Prove Drunk Driving?

Under Texas law, drunk driving occurs whenever someone operates a motor vehicle with a measured blood-alcohol concentration of at least 0.08 percent. This is not the only standard for drunk driving, however. In a criminal DWI case, a prosecutor may introduce other evidence, including police video of the arrest and even the expert testimony of toxicologists who regularly test blood, breath, and urine samples for law enforcement.

Court: Toxicology Expert’s Testimony Properly Admitted in DWI Case

Recently, a Texas appeals court affirmed a DWI conviction where the defendant challenged the admissibility of such expert testimony. The actual DWI arrest took place more than six years ago. A police officer said she observed the defendants committing “multiple traffic violations.”

During the officer’s subsequent traffic stop, she said she “detected an odor of alcohol” on the defendant. The officer then administered a number of standard sobriety tests to the defendant, which was recorded by her dashboard camera. Based on the defendant’s performances on these tests, the officer decided to arrest him for DWI.

At trial, the prosecution introduced the result of a blood test performed after the defendant’s arrest. The test indicated a blood-alcohol concentration of 0.092 percent, which clearly exceeded the 0.08 percent threshold in the Texas DWI law. The doctor who analyzed the blood sample also testified in court. He said that at 0.092 percent, a person would experience “euphoria” and “some level of impairment,” which in in turn “would affect your ability to make decisions.”

The defendant objected to this testimony as inadmissible under Texas court rules. The trial judge overruled the objection. The jury later found defendant guilty of DWI. The defendant appealed, but the Court of Appeals upheld the conviction.

With respect to the doctor’s testimony, the appeals court said he “possessed sufficient qualifications” to explain the “alcohol’s effect on the human body to the jury.” Furthermore, such general effects are not a “complex subject.” Nor did the doctor did not comment specifically on the effects of alcohol on this particular defendant. Indeed, the appeals court said the doctor’s testimony was not “central to the resolution of this case.” The police officer’s firsthand account of the arrest and the dashboard camera video, combined with the blood test results, was more than enough evidence to convict the defendant.

Have You Been Charged With DWI in Houston, Galveston, or League City?

In a drunk driving situation, everything you say and do matters. Remember, Houston-area law enforcement are trained to spot all potential signs of intoxication and impaired driving. Do not think that you can talk your way out of a DWI arrest or conviction. Drunk driving is a crime, and you need to treat it like any other criminal charge. The first thing you need to do is contact an experienced Galveston DWI defense attorney who can advise you of your legal rights. Contact the Law Offices of Tad Nelson & Associates today if you need immediate assistance.