Are Personal Breathalyzers Accurate Enough to Prevent a DWI in Houston?

Posted by Doug Murphy | Nov 27, 2019 | 0 Comments

For many Houston residents, having a drink after work or at a ball game is one of life's simple pleasures. Looming over every drink, however, is the risk of an arrest for driving while intoxicated. It should come as no surprise, then, that many drivers look for ways to stay out of trouble after a night of drinking. While many are content to take a rideshare or taxi home, others are unwilling or unable to leave their vehicle behind. Personal breathalyzers are the answer for some of these drivers.

The idea is simple: by carrying your own breathalyzer with you, you can test your blood alcohol concentration (BAC) before you drive. If your breathalyzer indicates your BAC is below the legal limit, you are good to drive, right? Unfortunately, it may not be so simple.

How Accurate are Personal Breathalyzers?

Like with any product including the breath machines used by Houston police officers, the quality of personal breathalyzers can vary dramatically. There are keychain breathalyzers available in many drugstores for a few dollars as well as specialty models that can cost several hundred. Unsurprisingly, the difference in accuracy between models is enormous. There are also other reasons why a personal breathalyzer should not be relied on.

Portable breathalyzers are very delicate devices. Even the units used by law enforcement are inaccurate if they are not properly calibrated. The same is true for personal models. If you fail to calibrate the device perfectly, it can give an incorrect reading. Jostling or shaking the unit after calibration can also skew the results. If you are not a trained professional, the chances are good you will be stuck with an uncalibrated breathalyzer at some point. Other factors that can lead to an incorrect reading include your body weight, lung capacity, and certain health issues you may have.

Even under the best circumstances, these devices still have a margin of error. High-end models advertise a margin of error of around .005 percent; easily enough to make the difference between being arrested for DWI or not. Cheaper models have an even larger range. Some are off by as much as .02 percent. Given the broad range of results, it is a risk to rely on these devices when you have been drinking.

What's more, the results of these tests are meaningless if you are pulled over. The officer that stops you will be uninterested in the results of a personal breathalyzer. Additionally, you will not be allowed to present evidence from your breathalyzer reading in court. With all of these factors together, relying on these devices is a risk not worth taking.

Arrested? Speak with a Houston DWI Defense Lawyer

Regardless of whether you used a personal breathalyzer before you drove or not, it is in your best interest to speak with a skilled defense attorney if you have been charged with a DWI. Attorney Doug Murphy has a long track record of successful DWI defenses in the Houston area. To learn more about your legal options in your case, schedule a free consultation with the Doug Murphy Law Firm, P.C. today.

About the Author

Doug Murphy

Doug Murphy is one of only two Texas lawyers Board Certified in Criminal Law by the Texas Board of Legal Specialization, and also in DWI Defense by the National College for DUI Defense, accredited by the American Bar Association and the Texas Board of Legal Specialization.


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