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Circumstantial Evidence In DUI Cases

Blood alcohol content tests, which are nearly always Breathalyzer tests, have acquired added significance over the past decade because Florida, like most other states, enacted a per se DUI law that defines intoxication as a .08 or above BAC. Nevertheless, about twenty percent of drivers still refuse to take a BAC test, and in the wake of the Supreme Court’s decision in Birchfield v. North Dakota, these drivers will face possible criminal sanctions.

In these instances, prosecutors must rely on 316.193(1)(a), and prove beyond any reasonable doubt that the defendant’s “normal faculties [were] impaired” by alcohol, a controlled substance, or a combination of the two. So, instead of direct evidence (the breath test results), the prosecutor must depend on circumstantial evidence. As a rule of thumb, it is always easier to challenge circumstantial evidence, and DUI field tests adhere to that general rule.

Unapproved Field Tests

Although the reciting-the-ABCs test, finger-to-nose test, and some other exams are not approved for use by the National Highway Traffic Safety Administration, many officers in the Treasure Coast area still use them. Often, they feel that these unapproved tests will fatigue the drivers and they will do worse on the tests that count.

In many jurisdictions, these tests may not be admissible for 316.193(1)(a) purposes, although the judge will almost never give the defendant any leeway in the next battery of exams because of these quasi-legal and scientifically unfounded tests.

Approved Field Tests

NHTSA has endorsed three field tests, and so they are always admissible for intoxication purposes. However, just because a government agency has endorsed their use does not necessarily mean that these tests are conclusive evidence of illegal impairment.

  • Horizontal Gaze Nystagmus: This test measures involuntary eye movements that are caused by excessive alcohol consumption and a few other factors. The subjects follow a specific point, like a fingertip, with their eyes without moving their heads. Although this test is about 80 percent effective under ideal conditions, roadside HGN tests are most certainly not conducted under controlled conditions.
  • Walk and Turn: This exam measures both mental acuity and physical dexterity. If the subject takes the incorrect number of steps or starts with the wrong foot, the officer will testify that the subject was intoxicated. If the subject uses arms for balance or cannot walk heel to toe, the officer will give similar testimony.
  • One Leg Stand: Lifting one leg for a certain number of seconds at a certain angle, and performing the test exactly as instructed, also measures the subject’s mental and physical abilities.

NHTSA insists that the tests are reasonably accurate in cases involving a BAC level over .04, so in some so-called “zero tolerance cases,” the entire Standardized Field Sobriety Test (SFST) battery may be completely unreliable.

Furthermore, in the latter two tests, the officers always testify that the subject “failed” the test, even if that conclusion is based on miniscule errors. However, given the nature of these tests and the wording of the law, there is ample room for a jury to disagree with that conclusion, and find that even though the defendant had been drinking, the defendant was not legally impaired.

Partner with Experienced Attorneys

Circumstantial evidence in DUI cases is subject to attack. For a free consultation with an experienced criminal defense lawyer in Port St. Lucie, contact Eighmie Law Firm, PA. We routinely handle matters in Lucie County and throughout the Treasure Coast.

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