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Need to Know Information

Driving While Intoxicated FAQs

What is DWI?

Houston DWI Attorney Tad NelsonDriving While Intoxicated (DWI) is a criminal offense that says a person may not drive a motor vehicle in a public place while “intoxicated.”

The Texas Legislature (Texas Penal Code (§724) 49.01) has defined a DWI as “not having the normal use of mental or physical faculties by reason of the introduction of alcohol, a controlled substance, a drug, a dangerous drug, a combination of two or more of those substances, or any other substance into the body” or “having an alcohol concentration of 0.08 or more”.

A prosecuting attorney needs to prove only one of these statements to the jury in order to get a guilty verdict.

What does “intoxicated” mean?

A person may be intoxicated in one of two ways. A person is intoxicated when, through the use of alcohol, drugs, a controlled substance or any combination thereof, loses the normal use of either his mental or physical faculties or has an alcohol concentration of .08 or more in his body.

Whose “normal mental and physical faculties” are we judged by and what is “normal?”

The DWI statute refers only to the faculties of the person being arrested. “Normal” refers to a range of measurement of the faculties of the person arrested. This refers to the mental and physical faculties as judged by the arresting officer, not by the person being arrested. So as you can see, this is very much a subjective evaluation.

There is not one specific point at which an arresting officer can say, with certainty, that you are not “normal”, but rather a range. On a scale of 1 to 100, most people would fall between 25 and 75, but this is agitated by many factors, such as weather, road conditions, or general nervousness.

What is a 0.08 alcohol concentration?

“Alcohol concentration” is defined by the statute as:

  • The number of grams of alcohol per 100 milliliters of blood
  • The number of grams of alcohol per 210 liters of breath; or
  • The number of grams of alcohol per 67 milliliters of urine.

It is important to understand that because the amounts of alcohol of the above concentrations are not equal, a person may not be guilty according to one concentration but guilty according to another. Also, it is possible to be considered intoxicated according to alcohol concentration levels, but have no loss of either normal mental or physical faculties.

Is it .08 or more when I drive or .08 or more at the time I’m tested, or both, that will make me guilty of DWI?

The Texas Penal Code stipulates that it is illegal to operate a motor vehicle with a Blood Alcohol Concentration of 0.08 or above in one’s body at the time of driving, not at the time of testing. This is of great concern for the accused because their BAC at the time of testing could be completely different than at the time of driving.

For example, suppose you have a couple of drinks in a short amount of time. Due to influences such as weight, stomach contents, etc., your body can only absorb so much alcohol at a time.

You are pulled over, and have a BAC of 0.04, then at the time of testing, you have a BAC of 0.1. According to the law, you were well within the limits, but this is just more ammunition for the arresting officer to take you to jail.

If I decide to submit to chemical testing and my alcohol concentration is less than .08, can I still lose my license?

If you submit to chemical testing at the time of arrest and the test results come back with a BAC of less than 0.08, than you still get to keep your license for the time being.

If you submit to testing, the only way that you can have your license revoked is if you are convicted of the DWI in a court of law. Only then can you lose your license, and only for the stipulated duration of time dictated by your conviction. Read more about DWI Penalties

How accurate and reliable are the police methods used to determine alcohol concentration?

If all of the tests are performed in a controlled environment, and are administered by a highly trained officer in the exact standardized manner, these tests can be a good indicator of intoxication. However, in reality these tests are never performed in this manner.

In a 1998 study, the National Highway Traffic Safety Administration retooled the field sobriety tests for the new 0.08 BAC levels, and they found the following results:

  • Horizontal Gaze Nystagmus can correctly identify a subject who has a BAC of 0.08 or higher in 88% of the time
  • Walk and Turn is correct 79% of the time
  • One Leg Stand is correct 83% of the time

That means that, even under laboratory conditions, these tests are inaccurate 21%-12% of the time. Under realistic roadside conditions, these percentages drop dramatically.

In the lab conditions there are no passing cars, wind, flashing lights, or other distractions. In the real world, of course, these factors exist. Nonetheless, Texas courts allow non-standardized testing to be admitted as evidence against you.

The state of Texas allows law enforcement agencies to test an individual’s BAC by means of either a breath, blood or urine test. While these tests might sound accurate to the uninformed person, in reality they leave much to be desired.

The problems with the breath test include improper calibration of the machine, improper use, improper instructions to the user, and the fact the police are not required to save your breath samples for future testing by an independent laboratory (as they have the capability to do).

This is especially important if you are an innocent person who fails the breath test, then your results cannot be verified and you will immediately go to jail. Most, if not all law enforcement officers in the state of Texas will neglect to inform you of your right to have your breath test checked by an independent lab.

If you submit to the breath test, insist that your breath sample be saved for independent verification. If the officer refuses, request to speak with your Houston DWI lawyer or criminal attorney immediately.

How is breath testing done?

What are the consequences of refusing the test?

Alcohol concentration testing in Texas is done using a machine called an Intoxilyzer 5000. This machine uses an infrared light to detect the amount of light absorbed by your breath.

The Intoxilyzer 5000
The Intoxilyzer 5000

The machine then compares this result to the amount of light absorbed by the ambient air, and that is your test result. If you blow a B.A.C. of greater than 0.08% or refuse the test altogether, you will face an immediate Administrative License Revocation (ALR).

Does a person have a choice to refuse a required breath or blood test?

By operating a motor vehicle on the roadways of Texas, you have given implied consent to submit to a breath/blood/chemical test. If you refuse these tests, than you are automatically subject to various surcharges and suspensions.

For the most part, these penalties are equal or greater than the penalties associated with a conviction for DWI.

Tad Nelson is an experienced defense attorney who has Provided Legal Representation in Clear Lake & Houston, Texas since 1992.

FAQs about Driving While Intoxicated

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