Houston applies the DWI/DUI laws of the state of Texas, and the answer to the question of how much you can drink without falling afoul of the law is more complex than it appears on the surface. In the case of alcohol, Texas measures intoxication by Blood Alcohol Concentration (BAC) – the percentage of ethanol in your blood.
Texas BAC Standards
Many people do not realize that Texas applies four separate BAC standards to drinking and driving:
- 0.08% BAC is the legal limit for a DWI charge, applicable to adult drivers (21 or over)
- 0.01% BAC (“any detectable amount”) is the legal limit for a DUI charge, applicable to minors (under 21)
- 0.04 % is the legal limit for commercial drivers (on duty and driving a commercial vehicle on a commercial driver’s license)
- 0.15% is the minimum for enhanced penalties (up to a year in jail for a first offense DWI or DUI).
Many variables determine how many drinks you can have before your BAC reaches the level of legal intoxication. Those BAC tables you might have seen on the Internet ignore most of these complicating variables. Some of the factors that influence how much you can drink and still drive legally include:
- Your body weight: The less you weigh, the less you can drink without exceeding the legal limit. Ten ounces of wine, for example, is likely enough to exceed the legal limit if you weigh 100 pounds.
- Fatigue: Fatigue increases BAC.
- Whether or not you drank on an empty stomach: Drinking on an empty stomach speeds up the process of intoxication and increases BAC.
- Whether or not you are under the influence of another intoxicant such as a prescription medication: A combination of results from a Breathalyzer (for alcohol) and a blood test (for prescription medication) could be enough to get you arrested for DWI even if your BAC is below the legal limit.
- How quickly you drink: The faster you drink, the higher your BAC is likely to be.
- How long you have been drinking: You might exceed the legal BAC standard during the tail end of a 12-hour drinking binge even if you slowed down to one glass of wine an hour for the last two hours.
- The alcohol content of the wine you are drinking: The alcohol content of wine typically varies from 9 percent to 16 percent.
Bruce weighs 160 pounds and drinks two five-ounce glasses of wine in an hour. Assuming that (i) he didn’t drink on an empty stomach, (ii) he was sober an hour ago (iii) he slept well last night (iv) he spaced his drinking evenly over the hour (he didn’t “chug” both glasses at the beginning or end of the hour) (v) the wine’s alcohol content was about 12.5% and (vi) his liver is functioning normally, his BAC is approximately 0.04% — legal to drive in Houston unless he is under 21 or a commercial driver.
Even in the foregoing scenario, Bruce could still be guilty of DWI if he was under the influence of a prescription drug that is intoxicating or that interacts with alcohol. Obviously, considering the number of variables involved it is best to leave yourself a wide margin of error.
Mario Madrid is a certified legal specialist in Criminal Law and a member of the National College of DUI Defense Attorneys. His two decades of legal experience includes time as both a prosecutor and judge as well as a criminal defense lawyer, If you have been charged with DWI or DUI in Houston, call Madrid Law, PLLC at 713-877-9400 for a free initial consultation.