Breath/Blood Tests and Conroe DWI Charges

DWI Attorney Helping Drivers in Conroe, TX

In Texas, the definition of "intoxicated" includes having a blood alcohol concentration (BAC) of 0.08% or more. In order to determine your BAC, the law enforcement officer will ask you to submit to either a blood test or breath test. The blood test will generally be conducted at the local hospital although it can sometimes be taken at the jail. The breath test will be taken at the jail or at jail substations.

Although a "failed" or "refused" breath or blood test may make it seem as though your chances of avoiding a DWI conviction are severely limited, this does not have to be the case. With experience in handling Conroe DWI charges, attorney Doug Atkinson can work to challenge this evidence against you, whether it is physical evidence or the arresting officer's testimony.

Get in touch with us today for aggressive defense.

Understanding the Breath Test

A breath test is conducted on a machine called an Intoxilyzer. Commonly, the breathalyzer utilized is either the “Intoxilyzer 5000” or “Intoxilyzer 5000en” depending on the county of arrest.

Intoxilyzer Definition

The Intoxilyzer breath test machine uses the spectroscopy method, which essentially measures the amount of light that is absorbed in a particular substance. The higher the concentration, the more light is absorbed and the higher the readout.

How is it administered?
You will be asked to blow into a mouthpiece. The air goes through a heated tube. Once the air enters the main chamber, light is shined into the cylinder.

The breath sample will absorb the light at a certain rate. The more light that is absorbed, the higher the concentration of alcohol. The machine will then compute the light absorption into a BAC value.

Is the machine accurate?
The government wants to use the results of the Intoxilyzer to prosecute you. However, there are many fallacies in the Intoxilyzer. For instance, a few areas of malfunction may include:

  1. The machine is only periodically checked for proper function and accuracy.
  2. The machine tests itself to determine if is malfunctioning.
  3. The machine is not required to perform perfectly by law.
  4. The machine has a rate of error of 0.02 allowable between the two breath specimens.
  5. The machine may be contaminated by previous users.
  6. The machine is not warrantied by the manufacturer to read accurately.
  7. The machine assumes everyone tested will have the same blood/breath ratio.
  8. The machine cannot tell what your BAC was at the time of driving.
  9. A fever may cause the machine to read higher.
  10. Some substances in your body may cause the machine to read incorrectly even though they are not alcohol.
  11. Radio frequency interference can cause the Intoxilyzer to read incorrectly.
  12. Mouth alcohol from belching can cause abnormally high readings.
  13. GERD or acid reflux can cause the Intoxilyzer to read incorrectly.

About the Blood Test

A blood test must be conducted under the rules of the Texas Transportation Code. The sample must be taken:

  1. At the request of a law enforcement officer;
  2. By a physician, qualified technician, chemist, registered professional nurse, or licensed vocation nurse;
  3. In a sanitary place.

How is the test administered?
The blood specimen is usually taken at the hospital by a nurse. The nurse will clean the injection area with an antiseptic. Then the blood is drawn into a tube and refrigerated.

Is it the test accurate?
A blood test may be inaccurate for several reasons. Your DWI lawyer can ask such questions as:

  1. Did the nurse who drew the blood use a non-alcoholic swab to clean the injection area? If the nurse used an alcohol swab the test results could be compromised.
  2. What type of container did the nurse use to collect the blood? If it was not a vacutainer tube containing an anticoagulant and sodium fluoride preservative, a whole blood test cannot be conducted because the results are not reliable.
  3. Was the blood immediately refrigerated? If the sample was not refrigerated the test results could be compromised.
  4. How was the BAC test conducted? If the technician did not use a gas-chromatography test then the BAC analysis may be inaccurate.
  5. When was the test taken? The blood test cannot tell what the BAC was at the time of driving only what it was at the time of the test.
  6. Was the blood properly handled and a “chain of custody” preserved to allow the blood to be utilized by the government at all in trial? If not, the blood will not be admitted into evidence.

Make sure you work with a lawyer who is experienced in challenging breath test and blood test results. Contact Conroe DWI attorney Doug Atkinson today.