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Laser DWI Detection

Speed Trap

Houston drivers are very familiar with the laser instruments used by police to enforce the speed limits. We’ve all been there: you’re driving to work, keeping up with the flow of traffic and, suddenly, every single car ahead of you slows down. That’s because just down the road, there’s a police officer parked and pointing one of those “speed guns” at the passing traffic.

Speed, or LiDAR (light detection and radar), guns use a finger-triggered laser to measure, in less than a second, the speed an individual car is traveling within a specific distance. Your car can be hit with a laser long before you even realize you’ve driven into a speed trap. Once you’ve been ticketed, it is hard to prove that the cops were measuring anything else other than your vehicle.

Since laser speed guns are so effective, you can imagine how excited the Houston police department must be at the prospect of using a similarly-designed laser gun to detect alcohol vapors as they are exhaled by a driver who has been drinking. Just point, shoot and boom — you’ve got your drunk driver, right? Well, not exactly. There are several issues I have with this potential scenario. But first, let’s take a look at this new technology scientists are hoping police all over the country will use in their DWI witch hunts.

Stand-Off Alcohol & DWI Detection

Scientists at the University Institute of Optoelectronics in Warsaw, Poland have built and tested a “stand-off detection” device that uses a laser to identify alcohol vapors in the cabin of a passing car. Yes, you read that correctly. In their testing, these researchers managed to simulate the presence of alcohol vapors that would be exhaled by an intoxicated driver in the car’s cabin by using an evaporated solution of alcohol “of an appropriate concentration and at an appropriate temperature.” (So, no, they didn’t test this device by putting a drunk scientist behind the wheel and zapping him with a laser!) Researchers foresee a future for this still-new technology in law enforcement, specifically for catching drunk drivers.

False Positives

Stand-off detection technology isn’t new, but the science and reliability of applying this technology to determine whether or not a moving driver is intoxicated is completely unknown.

As one of the most experienced DWI lawyers in Houston, I can foresee several problems with this imagined “laser gun” approach to trapping intoxicated drivers, including the following:

  • What if a passenger or passengers are intoxicated but the designated driver is actually sober?
  • What if some alcohol was innocently spilled in your car?
  • What exact alcohol level is the laser attempting to detect?
  • How does the laser detect ethanol to the exclusion of other chemical compounds, including isopropanol, methanol, acetaldehyde, toluene, etc.?
  • How does the laser distinguish between the breath of a diabetic, whose body is producing isopropyl alcohol, and the breath of an intoxicated driver?
  • What about perfume? Gasoline?
  • What if the windows are rolled down?

There are simply too many false positives that could compel an over-zealous police officer to then pull over and harass a sober driver, thereby abusing his or her constitutional rights.

Houston DUI and DWI Attorneys

Today’s methods and technology for detecting blood alcohol content and determining alcohol intoxication are seriously flawed as well. If you or a loved one has been arrested and charged with a DUI or DWI, contact Thiessen Law Firm today.

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