Proven Criminal Defense Attorney Representing Fort Worth and the Surrounding Vicinity

At the Fulgham Hampton Criminal Defense Attorneys , we receive many calls from clients with questions about breath testing in the field at the time of the arrest or later at the police station following an arrest for DWI. If you are under investigation for DWI or the surrounding areas of Texas, the police officer will generally request that you submit to chemical testing of your breath or blood to determine if you have a blood alcohol concentration (BAC) above the legal limit of 0.08 percent or above. Some people under investigation or subject to arrest for DWI in Fort Worth are unsure about their rights because there are two types of breath tests that are subject to different legal rules and objectives.

Portable Breath Tests (PBTs)

When you are stopped by a police officer who suspects that you are driving while intoxicated in Fort Worth or elsewhere in Tarrant County, you will typically be asked to submit to a roadside breath test along with field sobriety tests. The roadside breath test is conducted with a small handheld breath test device. The officer will ask you to blow into the device which will indicate whether your BAC level is over the legal limit of .08 percent.

Although the Texas informed consent law imposes consequences for a refusal to take a formal breath test following a lawful arrest, this law does apply to portable breath tests (PBTs). These tests are not admissible in court because PBTs are not particularly reliable. The device often has an adjustment screw on the side of the device that if manipulated will register an inaccurate result. While this is not to suggest that the officer would purposely distort your BAC results, the set screw on many handheld device can be set so that you are over the legal limit before you even breathe into the device.

PBT results are also not admissible because they are not specific for ethyl alcohol, which is the type of alcohol in beer, wine and liquor consumed as beverages. The device cannot distinguish ethyl alcohol from many other substances that mimic its effects. This means that the device lacks safeguards to allow it to avoid inaccurate breath testing results related to the following:

  • Mouth alcohol
  • Low carb diets
  • Diabetes
  • Mouthwash
  • Cough syrup

While portable breath test results are not admissible in a criminal trial for DWI in Texas, they may be used in an administrative hearing regarding suspension of your driving privileges. Further, the officer will use a test result that exceeds the legal limit as evidence of probable cause to support a DWI arrest. Although the officer may still arrest you based on observations of your driving, indicia of intoxication during the stop or field sobriety tests if you elect to perform these exercises, there is really no reason to agree to PBTs unless you are absolutely sure you are not over the legal limit for alcohol.

Fort Worth Breath Testing Following a Lawful Arrest

If you are arrested for DWI after being pulled over and subject to a DWI investigation in Fort Worth or anywhere in Tarrant County, you will be asked to submit to BAC testing of your blood or breath. Breath testing is more common because the Intoxilyzer 5000, which is used for evidentiary blood testing in Texas, is usually located at the jail facility. While you can refuse to submit to this formal BAC chemical testing at the police station, this refusal has consequences unlike roadside portable breath tests.

Before asking you to submit to a breath test, the officer must read you a DIC 24 DWI statutory warning. The warning will include but is not limited to the following:

  • A refusal by a driver over 21 to submit to breath or blood testing will result in a 180 day driver’s license suspension.
  • The suspension will apply regardless of whether the driver is prosecuted or convicted of DWI.
  • If the driver refuses to submit to BAC testing of the individual’s breath or blood, the prosecution can use this refusal in a DWI trial as evidence of consciousness of guilt.
  • If the driver provides a specimen and tests over the 0.08 BAC threshold, the driver will face a mandatory 90 day driver’s license suspension.

If you elect to consent to the breath test, this will usually occur with a specially trained Intoxilyzer 5000 operator at the police station/jail facility. The results of the test will be generated within seconds of submitting your breath sample for testing. At trial, the Technical Supervisor, who is responsible for maintenance and repair of the breath testing device will be called by the prosecution to testify that the machine was functioning properly when the test was performed.

The two breath test samples analyzed by the Intoxilyzer 5000 only need to be within twenty percent variance for the machine to be determined to be functioning properly. In other words, the device will be considered to be functioning properly if the driver tests .08 percent based on the first sample and .095 on the second sample.

The two models of the Intoxilyzer 5000 used in Fort Worth DWI cases are supposed to have “fail safe” features that prevent false results produced by confounding factors that compromised tests involving the Intoxilyzer. However, these features have been proven to be less than completely effective. Some example of factors that can compromise the accuracy of the results that the “fail safe” features are less than effective at addressing include:

  • Acetone in the breath caused by hypoglycemia associated with diabetes and low-carb diets
  • Mouth alcohol from residual alcohol in the mouth that has not be metabolized
  • Radio frequency interference

The manufacturer’s use of these “fail safe” measures can be used to confront the state’s expert regarding whether these types of issues can be an issue when conducting breath testing. Further, evidence can be produced of the defects associated with these “fail safe” features that can cause an inaccurate measurement.

These are just some of the ways Fort Worth DWI lawyers may challenge BAC chemical testing in a DWI case. Mr. Fulgham may also analyze whether the fifteen minute observation period to allow mouth alcohol to dissipate is observed or whether your blood alcohol level may have risen between the time the officer pulled you over and the time of the breath test. If you have been arrested for DWI, we invite you to call the Fulgham Law Firm P.C. so that we can guide you through the process. Call us at 817-877-3030 for a free consultation with a Fort Worth DWI lawyer.