If I Provided a Chemical Sample, Am I Automatically Guilty of DWI?

| Apr 6, 2019 |

If I Provided a Chemical Sample, Am I Automatically Guilty of DWI?This question comes up a lot, because most DWI cases in Tarrant County are test cases. Sometimes, defendants do not fully understand their right to refuse a breath or blood test. Other times, quite understandably, defendants want to cooperate with law enforcement so they do not make deep legal holes even deeper.

Back in the day, a BAC above .08, or whatever the legal limit is in that situation, was only a presumption of intoxication. But Texas lawmakers changed a key provision of Section 49.04 in the Texas Penal Code. So, drivers who have a BAC above the legal limit are now intoxicated as a matter of law. As a result, the conviction rate in test cases is about twice as high as the conviction rate in non-test cases.

For this provision to apply, the state must prove that the defendant had a BAC above the legal limit and not just prove that the defendant took a test. That gives a Weatherford criminal defense attorney an opening.

Blood Tests

Admittedly, blood tests are hard to successfully challenge. The conviction rate is over 90 percent in these cases. Fortunately, the Supreme Court recently ruled that police officers must obtain search warrants before they forcibly extract blood samples. Typically, officers do not want to take that extra step and mess with the additional paperwork.

There are a few “no-refusal” weekends on the calendar, mostly around holidays like Labor Day and New Year’s Eve. During such heightened enforcement periods, supervisors require officers to obtain search warrants if the driver refuses to blow into a Breathalyzer. But these no-refusal weekends are few and far between.

Sometimes, there is a gap in the chain of custody. From a legal standpoint, such gaps may affect the integrity of the evidence. Additionally, if an attorney orders a blood sample retest, findings from an independent laboratory are sometimes different from the police laboratory results.

Breath Tests

So, nearly all test cases involve Breathalyzer tests. The conviction rate in these cases is still quite high, but it’s not as high as blood test cases. In other words, Breathalyzer tests give defendants more of a chance.

To authenticate Breathalyzer results, Tarrant County prosecutors usually call police technicians to the stand. These technicians try to dazzle the jury with talk of biological/electrical conversions and fuel cell response levels. But take away the bells and whistles, and the Breathalyzer is basically a 1950s Drunk-o-Meter.

Perhaps more importantly, the Breathalyzer does not measure blood alcohol content. It measures breath alcohol content and uses that number to estimate blood alcohol content. That extra step leads to test issues like:

  • Mouth Alcohol: Over the years, courts have watered down the pre-test monitoring requirement so much that it is almost meaningless. This change actually helped defense attorneys. If the driver belches or burps in the half-hour prior to the test, alcohol particles flood the mouth. So, the breath alcohol level, and the BAC estimate, are artificially high.
  • Unabsorbed Alcohol: Most liquids go from the stomach to the bloodstream. But most alcohol goes from the stomach through the liver and then to the bloodstream. So, if the defendant has been drinking in the hour before the breath test, that alcohol is not yet in the bloodstream, so once again, the BAC estimate is artificially high.

To drive home flaws like these, many criminal defense attorneys partner with degreed chemists. These individuals are much more persuasive than the Breathalyzer techs that prosecutors normally use.

Even if the defendant provided a chemical sample, a not-guilty DWI verdict is still possible. For a free consultation with an experienced criminal defense attorney in Weatherford, contact Herreth Law. We are available for help 24/7/365.