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Intoxicated Driving: Understanding Blood Tests

Intoxicated driving in Texas is a serious criminal charge. During a DWI investigation, an officer may request a blood sample. This is especially true when an alleged suspect refuses a breathalyzer test or a police officer believes the suspect is intoxicated by drugs. If you do not agree to it, a warrant may be issued, and at that time, a blood sample will be taken with or without your consent. A lot of confusion surrounds what your rights and obligations are with respect to drunk driving and blood tests. To do one thing and not the other can have a significant impact on any criminal charges laid against you or administrative penalties imposed on you in Texas.

At Sobel Law Firm, our DWI defense attorney in Humble, Texas wants to ensure you, as our client, are informed and understand both your rights and the consequences that flow from missteps taken when encountering the police during a DWI investigation. Contact us today at 713-528-5200 to schedule a Free Consultation.

What are DWI Blood Tests?

DWI blood tests are chemical tests commonly used in Texas by the police to determine or verify whether and to what extent an individual unlawfully has alcohol or drugs in their system. It is used most often in two circumstances:

  1. The alleged drunk driver has refused to perform a breath test; and/or
  2. The police believe the driver might be under the influence of drugs, which can include prescription medication or any type of illicit drug.

Blood tests produce more accurate results than the other two chemical tests associated with intoxicated driving cases: breath tests and urine tests. A blood test is also much more intrusive. With breath tests, you simply blow into the testing machine. With urine tests, you urinate into a cup. With blood tests, however, a qualified medical professional must draw blood to collect a test sample.

Can I Refuse a Blood Test in Texas?

The simple answer is yes. Keep in mind, however, that a refusal in Texas can have significant consequences. The same is true even if you are never convicted of an intoxicated driving offense in Humble, Texas because you will still be hit with administrative penalties.

The problem is this: implied consent laws.

When you obtain a driver's license and drive anywhere in the United States, you have implicitly implied to agree to obey the laws of each state, and each state has its own version of implied consent laws. Basically, by agreeing to obey the rules of the road, you also implicitly agree to chemical tests.

Thus, if you are suspected of drunk driving and are asked to consent to a breath or blood test but refuse, there are automatic administrative penalties placed on you. These penalties include fines and license suspension.

If you do refuse to give a blood sample (or refuse a breath sample), the police can quickly obtain a warrant to collect a sample. In the end, if you refuse, you will likely still have to give a blood sample.

When Are DWI Blood Tests Allowed in Texas?

Police must have probable cause that you have been driving under the influence of alcohol or drugs before they can administer a blood test. Probable cause can be obtained many ways, like slurred speech, a failed sobriety test, or the smell of alcohol or drugs, among other potential indicators.

If probable cause exists, a blood test can only be administered in most states if one of the following occurs:

  • The driver signs a waiver.
  • The driver consents.
  • The police officer obtains a search warrant authorizing the blood test.
  • Exigent circumstances exist and qualify as an exception to the search warrant requirement.

DWI Blood Tests in Texas Can Be Unreliable

Blood tests provide better results than breath tests. Not only can a blood test determine a more accurate blood alcohol content (BAC) level, but it can also identify specific drugs and the amount of those drugs in your system.

That said, even if they are more accurate, they can still be unreliable when certain issues are present.

Common situations that could lead to the suppression of a blood test result in DWI cases in Texas include:

  • Too long of a waiting period between arrest and administration of the blood test
  • Contamination of the blood sample
  • Improper preservation or storage
  • Improper transportation of the sample
  • A gap in the sample's chain of custody
  • Drawing of the blood sample by an unqualified person

In addition, the technology and machines used to analyze the blood samples could have problems that make the results unreliable. These machines require regular maintenance but are often neglected.

DWI defense attorneys in Humble, Texas who have the right experience, knowledge, and skill in these types of cases will be able to identify unreliable blood test results. A motion to suppress or exclude the results can be timely filed and strategically used in your defense.

How DWI Defense Lawyers Can Challenge Blood Tests

DWI blood tests can be excluded from evidence under certain circumstances. A defense lawyer should identify when those circumstances are present and take immediate action to exclude the evidence.

As noted above, a court can exclude blood test results when conditions make the results unreliable (e.g., mishandling of the sample). The court may also suppress blood test results when a defense lawyer can prove there was:

  • Prosecutorial misconduct
  • Police misconduct
  • Issuance or enforcement of an invalid warrant
  • Violation of your constitutional rights

When blood tests are admitted into evidence, your defense attorney still has options. For example, they can

  • Retain an independent lab to perform additional blood testing
  • Hire an expert to testify about any circumstances that could have produced inaccurate results

Finding the right DWI defense lawyer in Humble, Texas will be key to a successful outcome in your DWI case.

Contact a Skilled DWI Defense Attorney in Humble, Texas Today

At Sobel Law Firm, our DWI defense attorney understands the complex nature of Texas intoxicated driving laws, the technical and scientific aspects of blood tests, and how to strategically fight the allegations to get the best outcome in your unique case.

We want you to know that just because you are charged with DWI offenses, it does not mean you will be found guilty. You can successfully defend against these types of charges, but you need an DWI defense lawyer who can help you do it. Call our office today at 713-528-5200 or fill out an online form to schedule a Free Consultation.

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