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The Matassini Law Firm, P.A. Your trusted legal advisors since 1976

Beating Chemical Tests in DUI Cases


Modern Breathalyzers first appeared in the United Kingdom in 1967. By 1980, they were standard equipment for most police officers in Florida. The latest generation Breathalyzers are even more sophisticated. For example, they use fuel cells to trigger electrochemical reactions instead of crystals which usually require bodily fluid samples.

Shortly after Breathalyzers appeared in the United States, most jurisdictions, including Florida, changed their DUI laws to keep pace with this technological change. Today, persons who provide chemical samples above a certain level are guilty of DUI as a matter of law. These levels are normally .08 for noncommercial drivers and .04 for commercial operators. Trace amounts of alcohol are sufficient to convict any motorist under 21.

The conviction rate for test cases is much higher than the conviction rate in non-test cases. That’s especially true for blood tests. However, chemical tests also have a number of moving parts. If one segment is not up to snuff, the results could be invalid. An experienced Tampa criminal defense attorney concentrates on some common chemical test flaws.

Blood Test Flaws

Scientifically, blood tests are much more accurate than breath tests. However, officers must obtain search warrants before they can extract blood samples. Therefore, blood tests are usually limited to No-Refusal Weekends and other heightened enforcement periods.

Blood tests are scientifically accurate, but often they are not legally compelling. Samples must make multiple stops in their journey from a driver’s body to a criminal courtroom. Any procedural irregularities along the way could invalidate the sample.

Additionally, defense attorneys usually order re-tests in blood test cases. Frequently, an independent laboratory obtains a much different result from the one that a police technician claims s/he obtained.

Breathalyzer Flaws

These gadgets use basically the same technology as the Drunk-O-Meter, a device which was invented in 1931. So, although modern Breathalyzers have lots of bells and whistles, they rely on ancient technology. Largely because of this reliance, they have a number of specific flaws. Some of them include:

  • Mouth Alcohol: If the driver burped or vomited in the fifteen minutes prior to the test, alcohol particles from the stomach rush into the mouth, thus skewing the results. Police officers are supposed to monitor defendants before they take Breathalyzer tests, but effective monitoring is rare.
  • Unabsorbed Alcohol: Breathalyzers do not account for the alcohol digestive process. Normally, alcohol travels from the stomach to the liver to the blood. So, if the driver had been drinking within the last hour or so, the unabsorbed alcohol artificially elevates the BAC estimate.
  • Temperature Changes: Like most scientific instruments, Breathalyzers are sensitive devices, especially regarding temperature. That includes the test subject’s temperature as well as the outdoor temperature. Many people drive with mild fevers. Additionally, extreme temperature changes are common in Florida during certain months.
  • Calibration: On a related note, the Breathalyzer’s many moving parts require frequent calibration. In 2017, an investigation determined that almost all the Breathalyzers in Massachusetts had been improperly calibrated for years. As a result, a District Judge declared that Breathalyzer results were presumptively unreasonable.

To drive home these flaws, and others as well, attorneys often partner with degreed chemists who testify for the jury. Chemists have much more credibility than police department Breathalyzer techs. 

Rely on Experienced Lawyers

DUI chemical test results are not always accurate. For a free consultation with an experienced Tampa DUI lawyer, contact The Matassini Law Firm. We routinely handle matters in Hillsborough County and nearby jurisdictions.


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