Statistics vary by jurisdiction, but generally, the conviction rate in DUI test cases is over 85%. However, if the defendant refuses to provide a chemical sample, the conviction rate drops to about 45%. The conviction rate drops so sharply because, in non-test cases, Michigan prosecutors cannot use the per-se portion of the DUI law. Instead, they must rely on circumstantial evidence to secure a conviction. Just like in other types of cases, it is much easier for an aggressive attorney to challenge this type of evidence.
In DUI cases, the circumstantial evidence almost always comes from three field sobriety tests. Flint officers may administer other tests, such as the finger-to-nose test. There is almost no scientific evidence in support of these unapproved tests, however, so they are usually only admissible for limited purposes.
In many ways, the walking-the-straight line test is the quintessential intoxication test. It is a divided attention test that measures both manual dexterity and mental acuity.
The officer asks the defendant to walk heel to toe for a certain number of steps along a straight line, then turn around and walk back heel to toe. During the test, the officer looks for a number of clues, including:
If the defendant exhibits more than four clues, there is statistically a good chance that the defendant is intoxicated.
The problem with this test is that the conditions are usually quite bad. Generally, the defendant takes the test outdoors and at night, while cars whizz by and the police car’s overhead lights flash in the defendant’s eyes. Making matters worse, some defendants must walk an imaginary line instead of an actual line. Deficiencies like these make the WAT almost inherently unreliable.
Much like the WAT, the OLS is a divided attention test. Most researchers believe that people who are intoxicated cannot multitask. Also like the WAT, the officer looks for clues during the OLS. Some of these clues include:
Based on the clues, these two tests have a lot in common. Officers also grade them in much the same way. Especially in the OLS, officers often say that the defendant “failed” the test based on a rather minor deficiency, such as a slightly-incorrect angle or a nearly imperceptible sway. Fortunately, a Flint jury is usually not as particular, and their grade is the only one that counts.
In this test, defendants must track moving objects with only their eyes; the moving object is usually an ink pen, an index finger, or a flashlight bulb. Nystagmus, or involuntary eye movement, is rather easy for trained officers to spot. The problem is that alcohol is not the only cause of nystagmus. In fact, it is not even the leading cause of nystagmus.
Test conditions are usually an issue, as well. The flashing lights mentioned earlier are particularly troublesome in a vision test. Nystagmus clues are also much more difficult to see in the dark.
Prosecutors must rely on rather flimsy evidence in circumstantial DUI cases. For a free consultation with an experienced criminal defense attorney in Flint, contact Nickola Law. Convenient payment plans are available.
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