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DWI Blood Testing

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Our Houston DWI Attorneys Know How to Challenge Blood Test Results

The legal standard for intoxication in Texas is a .08 blood alcohol level (BAC), which can be measured by breath or blood. To find it in blood, it is measured against 100 milliliters of your blood. A blood test is the last thing you want to happen. It’s invasive and unpleasant, plus it’s harder to fight in court. Both blood and breath tests have their fair share of flaws, but contesting a blood test requires a little more footwork.

If you have failed a blood test after a DWI arrest in the Houston areaThiessen Law Firm is here to help. These cases are difficult to win, but they are not impossible. Attorney Mark Thiessen is Board Certified in DWI Defense Law by the National College for DUI Defense, and has won countless blood test trials, from 0.06 up to a 0.29 blood alcohol level. He has also won cases involving blood tests with serious accidents and fatalities involved.

Do I Have to Give the Police a Blood Sample?

It is your constitutional right to refuse a blood test. HOWEVER, if you can you should avoid getting to this point because Texas can suspend your license and use your refusal as evidence in future prosecutions against you. And, in many jurisdictions, they will get a warrant for your blood 24/7.

Blood Alcohol Testing Procedures

Before having to refuse or consent to a blood test, you will normally have the option to take a breath test and/or a standard field sobriety test first. If you refuse to take all of these, they will take you to the police station and read you your rights regarding the blood-alcohol tests. Then here’s what you do:

  1. Ask them what happens if you refuse the breath test again.
  2. Most officers will answer that if you refuse the breath, they will take your blood instead.
  3. After they’ve said this, take the breath test over the blood test!

In most scenarios, officers cannot take your blood until you refuse a breath test. If you fail either test, you may lose your driving privileges: 90 days for a first offense and one year with suspicion or conviction of alcohol-related charges within the preceding 10 years.

Why take a breath test over a blood test?

  • If you refuse the breath test, they can use that refusal as evidence of your guilt.
  • When they take your blood, they will always take two vials; the State will argue the second is for the Defense to test if they don’t trust the result.
  • They can test your blood for drugs and medication, which they can’t do with a breath test.
  • Many jurisdictions won’t allow you into dismissal programs if you refuse a breath test.
  • Juries tend to trust blood results more than breath results.

You have 15 days to save your driver's license

Act fast if you've been charged with DWI or DUI in Texas. Here’s something you might not see from other Houston DWI Lawyer websites: If you've been arrested for a DWI or DUI in the state of Texas, you are facing two cases against you. The first one is the criminal case by the state of Texas, and the other is by the Texas Department of Public Safety to suspend your license.

License Suspension

When You HAVE to Give Them Blood

Texas has recently implemented no refusal weekends, which aren’t just limited to holiday weekends. During no-refusal time periods, the Texas Supreme Court allows police officers to draw blood without your consent, based only on probable cause.

If you resist, they really will strap you down to a chair using as many officers as they deem necessary until they have gotten your blood. If this happens, don’t fight. At that moment, there is no way around it and you don’t want to risk suffering bodily harm from the police – or an assault charge if they feel you fought back too hard. Afterward, you should contact a qualified DWI or DUI lawyer as soon as possible to rectify the situation.

Few Lawyers Can Help if You Fail a Blood Test

The truth of the matter is that less than 1% of lawyers are skilled enough to win a DWI case if you’ve failed a blood test. It’s one reason lawyers recommend that you avoid blood tests entirely.

As a trial attorney focusing on complicated DWI cases, Mark Thiessen is one of the few attorneys trial-tested and proven in this area of the law. Not only does he know constitutional and DWI law inside and out, but he understands the scientific and technical aspects of these cases better than the experts. Mark Thiessen has won three blood test trials where the blood comes into evidence and the jury returns a verdict of Not Guilty (.022, 0.19 and 0.09). Anyone can win a trial with the blood suppressed. You need an attorney who can win with the blood coming in.

At best, blood tests are an approximation of your BAC with an “acceptable” error range of error, but even so, a comprehensive understanding of the number of scientific fields is required to effectively argue a blood test case in court. Any given DWI or DUI case may require courtroom back-and-forth involving anatomy, physiology, toxicology, chemistry, medicine, chemical testing, computer science, biology and even physics.

Contact Our Houston DWI Lawyers Today

Technical expertise and aggressive defense counsel are a must in the face of a DWI blood test. Thiessen Law Firm has the talent and dedication you need to fight back against a “failed” blood test, and we are not afraid to go to court for you.

Contact Thiessen Law Firm at 713.864.9000 or request a free case evaluation online. We are available 24 hours a day, 7 days a week to ease your concerns and protect your freedom.

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