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Circumstantial Evidence in Alcohol-Related Offenses

In most prosecutions, a breath sample creates a presumption of intoxication in a DUI case. This presumption can be overcome by introducing evidence concerning flaws in the test, such as a failure to account for elevated acetone levels, or flaws in the procedure, such as a failure to observe the suspect for at least fifteen minutes prior to the test.

But in about one in five cases, the suspect either refuses to provide a breath specimen or is unable to provide this specimen, and officers only obtain search warrants for blood tests in a handful of these situations. So, the vast majority of refusal prosecutions rely on circumstantial evidence.

DUI Field Tests

Many officers use informal field tests, like reciting the ABCs, touching the tip of one’s nose, counting from one number to another one, or answering a trick question such as “what was the year of your first birthday?” There are three field tests that are approved by the National Highway Transportation Safety Administration, and each one has serious potential flaws. NHTSA claims the tests are about 90 percent accurate overall.

In addition to measuring physical coordination and balance, officers use the walk and turn (WAT) test to assess the suspect’s mental capability through the ability to follow directions. The suspect is told to walk a certain number of steps in a straight line heel to toe, beginning with either the left or right foot.

One problem with the WAT is that, in many cases, the suspect is told to walk an imaginary line as opposed to a parking lot stripe or other actual line, and it is much harder to perform the former than the latter. Furthermore, many police cars are equipped with “takedown lights,” which got their name because they visually disable suspects. It is almost impossible for anyone to walk a straight line under these uncontrolled conditions.

The one legged stand (OLS) suffers from many of the same deficiencies as the WAT. There is a great deal more technical proficiency required in this test as well; for example, many officers gladly point out to the jury that the suspect started with the wrong foot, held it up at a slightly incorrect angle, or held the foot up for a millisecond too long.

Finally, there is the horizontal gaze nystagmus (HGN) test: the suspects must track a moving object, like a pen head or fingertip, without moving their heads. If a suspect exhibits at least four “clues” in the test, which are basically involuntary eye movements, there is about an 85 percent chance that the person is intoxicated.

The 85 percent figure commonly cited assumes that the test was conducted under controlled conditions, indoors, and with plenty of light. Most HGN field tests occur at night with flashing takedown lights in the background, and these conditions are far from ideal.

Field Tests and the Standard of Proof

In nearly all cases, even if the suspect seemingly performed the test rather well, the officer testifies that the suspect “failed” the test. But the real question is not pass or fail, but whether the suspect’s performance gave the officer probable cause to arrest the suspect. That phrase is not really defined anywhere in the law. It is up to a jury, and not the arresting officer, to decide whether or not the arrest was proper.

Contact Aggressive Lawyers

In any criminal case, the defendant can attack the prosecutor’s evidence. For prompt assistance in this area, contact an assertive criminal defense attorney in Port St. Lucie. At the Eighmie Law Firm, P.A., jail visits are available.

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