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Are blood tests more accurate than breath tests? Blood tests are not always reliable.

About David Breston
The Breston Law Firm has handled over 4,000 cases and has been helping people in Texas since 1987. Watch this video to find out more about our firm

Learn how to choose a DWI lawyer and the importance of choosing an experienced attorney.

A Texas DWI charge can cost you to lose your license, you face fines and may cost you your job.

Have you been charged with Driving While Intoxicated (DWI)? Watch this video by David Breston explaining how he may be able to help you.

Should you refuse a breath test if you are pulled over for DWI in Texas? Watch this video to learn.

Reliability of Breath Test Results in a Drunk-Driving Case

The most common tool used by law enforcement to determine a driver's blood alcohol content level is the breath test. However, it has lately been the subject of much controversy because it has been shown time and again to be an unreliable indicator of authentic blood-alcohol content level results. Let's first consider the definitions of some of the more pertinent related language.

BAC – blood alcohol content (also termed blood alcohol concentration). It is a metric of the level of intoxication used for medical or legal purposes and indicates the percentage of alcohol in an individual's blood. As an example, if you were to have a blood alcohol content reading of 0.10% then this would mean that 1/10 of 1% of your blood is actually alcohol.

Breathalyzer – a device for determining the blood alcohol content of an individual through a sample of his or her breath. Originally a brand name (think kleenex) it has morphed into a generic term for any machine that can perform this function. A breathalyzer is considered to be a scientific device. According to law enforcement, the advantage of its use is its non-invasive ability to gauge a level of intoxication versus medically withdrawing a blood sample with the use of a needle. Scientifically speaking, when a person drinks alcohol it is not digested but, rather, absorbed through the membranes in one's mouth and throat, stomach and intestines. From here it passes into the blood stream and leaves the body when a person exhales. The amount of alcohol in each exhalation is equal to the amount of alcohol in one's bloodstream. When a person breathes into a breathalyzer the air mixes with a chemical solution that causes a color change that is compared to a color chart for interpretation.

To the layman it may sound infallible but consider the following problems that have occurred.

  • The machine must be calibrated on a regular basis. This requires the intervention of an expert – not every police officer has this capability.
  • Breathalyzers are sensitive to light, heat and humidity. Think a police car on a hot summer night and you would agree that the 'room for error' with these instruments skyrockets.
  • Interpretation of the results is not always accurate – even when done by people who were 'trained' in the use and manipulation of breathalyzer devices and results.
  • Products other than alcohol can trigger the breathalyzer. For instance, mouthwashes all have some level of alcohol in them that could be picked up by the breathalyzer.

Most unsettling of all is the fact that police departments across the country have been found to admit to the unreliability of these machines In Virginia, an internal forensics document was uncovered that stated the current breathalyzers in use by law enforcement were 'unreliable and outdated'. In New Jersey, the judge himself threw out a DUI case after calling the breathalyzer results unreliable. Finally, there is evidence that police officers themselves have been found to tamper with the breathalyzer results.

In a DUI case – always contest breathalyzer results. If this is the basis for the arrest – it could very well have been false.

When your future is at stake, it is important that you enlist the
assistance of a DWI defense lawyer who not only understands
your situation but also has a thorough knowledge of the drunk
driving (DWI) laws and procedure in Texas. Mr. Breston
devotes himself to examining all aspects of your case in
order to construct the strongest possible defense on your
behalf. Let him conduct an investigation and determine the
best way in which to pursue a resolution to your situation.

as soon as possible for a free consultation.
He can help you fight for your rights.

Serving clients throughout Texas, including Houston, Galveston, Angleton, Pearland, Alvin, Sugar Land, Clear Lake, Conroe, Pasadena, La Porte, Missouri City, Texas City, Friendswood, Richmond, Rosenberg, Corpus Christi, Brownsville, San Antonio, Laredo, Austin, San Marcos, Dallas, Denton, Plano, Lubbock, Midland, Anahuac, Beaumont, Hempstead, Huntsville, Liberty, The Woodlands, Humble, Tomball, League City, Bellaire, Deer Park, and Katy and other communities in Harris County, Brazoria County, Fort Bend County, Montgomery County, Galveston County, Chambers County, Liberty County, Jefferson County, Waller County, and Walker County.