Contact Us for a Free Consultation (713) 229-0862

Useful Information

If I get pulled over, should I agree to take a breath test? What about a blood test?

Posted by Ed McClees | Dec 20, 2018

Do not be fooled by law firms that aggressively market on billboard, radio and through cleverly worded slogans about whether you should or should not provide a breath sample. The truth is that there is no “one size fits all” answer to this question, because each situation is unique. 

At the end of the day, a breath test or blood test is simply another piece of evidence. And in some situations, you may not have a choice. In Harris County, for example, if you do not volunteer to provide a breath test, the police officer will obtain a search warrant for your blood. Other counties also have “no refusal” programs in place on weekends and around holidays. These programs make it quicker and easier for officers to obtain search warrants that allow officers for forcibly take a blood sample from someone suspected of driving while intoxicated. The good news is that like any other piece of evidence, these tests can be successfully attacked at trial by an experienced defense lawyer.

While law enforcement in Texas used to use a device called an Intoxilyzer 5000 to do breath testing, these outdated machines have been phased out and replaced with the newer Intoxilyzer 9000. The basic theory behind how the machines work remains that same. When you blow into the device, air is captured in a small tube. An infrared light is then shined into the tube, and a device measures the amount of light at the end of the tube. The theory is that alcohol will absorb some of the light, so if there is alcohol in the breath, less light will get through. The problem is that other substances absorb light at a similar rate to alcohol. Further, mouth alcohol and other interferents can lead to artificially high results. Simply put, the machine is better at detecting whether alcohol is present than it is at determining the precise amount of alcohol that is in the breath. We have the experience to spot these and other problems that exist in the breath test machine.

Blood testing is done through a process called gas chromatography. For this process to work properly, the machine must separate alcohol from all other substances that can be found in the blood. Because human blood contains thousands of substances, this is no easy task. If the alcohol is not properly separated, then the results are useless. Further, the text book that is used to train blood analysts warns that in some situations certain microbes can actually create alcohol in the test tube before the blood is tested, which will result in an artificially high reading. While there are a lot of law firms who will gladly take your money to handle your DWI, you need to hire a lawyer who has the experience to challenge these tests in court. We have that experience and have successfully defended people charged with DWI who have given a breath or blood sample to law enforcement.

About the Author

Ed McClees

Ed is a criminal trial lawyer who is Board Certified in Criminal Law by the Texas Board of Legal Specialization.  He is a former Harris County District Attorney where he served as chief of the Organized Crime Section, prosecuting cases involving complex organized criminal activities, including Fr...

Contact Us Today

If you have been charged with a crime or are concerned that you are being investigated for a crime, call us immediately. Please provide a personal email and a cell phone number so that we can immediately reach you. We will put our years of experience and proven results to work for you.