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Fighting The Evidence In A DUI Case


Like most states, Florida’s DUI law contains a per se section and an “impairment” section. Defendants are guilty as a matter of law if their BAC exceeds the legal limit, which is usually .08. If the defendants refused to provide chemical samples or they are unavailable for whatever reason, the prosecutors must establish that the defendants lost the normal use of their “normal faculties.” In both these instances, the state must prove that the defendant was “driving” the vehicle.

All these areas may be subject to collateral attack.


In Florida and most other states, “driving” in this context is more like “operating,” because the vehicle does not have to be in motion to support a DUI conviction. Instead, the defendant must:

  • Have the ability to put the vehicle in motion (g. the ignition must be on), and
  • Possess the intent to driver the vehicle in the ordinary sense of that verb.

Some situations are rather uncertain. For example, what if the defendant was sleeping behind the wheel of a parked car with the ignition on (ability but no intent)? Or, what if the defendant was behind the wheel of a car but the keys weren’t in the ignition (intent but no ability)? These situations, and others like them, may create enough reasonable doubt as to this element to convince at least one juror to vote not guilty, and that is all that is required.


Since officers must obtain search warrants to administer blood draws, nearly all DUI test cases involve Breathalyzers. Although the device has been improved significantly since it first appeared in the 1950s, it still uses basically the same technology and is therefore still subject to basically the same flaws:

  • Acetone: Many people, including smokers and diabetics, have high acetone levels in their bloodstreams, and Breathalyzers normally register this substance as ethanol.
  • Absorption: If the defendant had anything to drink within the last hour or two, the alcohol may not be fully absorbed into the bloodstream and the Breathalyzer results may be inaccurate.
  • Mouth Alcohol: Defendants who belch or burp within the fifteen minutes prior to the test release additional alcohol into their mouths, affecting the Breathalyzer test results.

Breathalyzers do not measure blood alcohol content. Instead, they measure breath alcohol content and then estimate the blood alcohol level. That’s why, many times, the results may be fundamentally flawed.

Loss of Function

If a chemical sample is unavailable, prosecutors must use circumstantial evidence to prove loss of normal faculties, and this evidence normally comes from the three approved field sobriety tests. Many departments use unapproved tests as well, but the results are usually only admissible for limited purposes.

  • OLS: Officers often testify that the defendant “failed” the one leg stand because of minutiae like starting with the wrong foot, but the jury decides who “passed” and who “failed” this and other FSTs.
  • HGN: The horizontal gaze nystagmus test is supposedly quite reliable, but if the test does not take place under carefully controlled conditions, the results are much more uncertain.
  • WAT: The walk and turn test, a/k/a the walking a straight line test, also depends on test conditions, because it is much easier to walk heel-to-toe over an actual line instead of an imaginary line, and so on.

The prosecutor must prove that the defendant lost function and that this loss was due to alcohol or drugs.

Go with Assertive Attorneys

The evidence in DUI cases is subject to challenge. For a free consultation with an experienced criminal law attorney in Port St. Lucie, contact Eighmie Law Firm, P.A. Home and jail visits are available.



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