A Pennsylvania DUI prosecution typically involves a broad spectrum of scientific evidence involving physiology, chemistry and psychometrics. Many drivers arrested for DUI in Pittsburgh and throughout Pennsylvania assume that the science behind the evidence typical in a Pennsylvania DUI prosecution is solid and reliable. In reality, one of the reasons that an experienced DUI defense attorney frequently can provide an effective defense to DUI charges is that the scientific reliability behind DUI evidence is shaky at best.
Most DUI investigations begin with the police officer making observations during a traffic stop of the vehicle. The officer will typically point to observations of physiological symptoms including bloodshot watery eyes, slurred speech and lack of coordination. However, these physical observations have very little connection to intoxication. These symptoms are equally connected to such a broad range of physical conditions as diabetes, allergies, lack of sleep and illness (flu or cold). These are only a few common examples that show the general lack of reliability of typical police observations.
The next type of unreliable evidence that police and prosecutors typically rely on in a Pennsylvania DUI case are Field Sobriety Tests (FSTs). These tests are hardly more reliable than the observations of the police officer. When the officer has been trained properly and conducts the FSTs perfectly, the tests are still appallingly inaccurate. While these are supposed to be standardized tests conducted according to detailed instructions, the tests are often administered incorrectly or the officer fails to give proper instructions. Although only 3 FSTs have been shown to have any more reliability than flipping a coin, officers sometimes administer FSTs that have been shown to have virtually no probative value.
Even when officers use one of the three tests that have better than 50-50 accuracy, they still have a ludicrously high false positive rate when conducted perfectly. Most people would be surprised by rate of inaccuracy with even the 3 approved FSTs:
- Horizontal Nystagmus Test: Inaccurate 23% of the time
- Walk and Turn: Inaccurate 32% of the time
- One Leg Stand: Inaccurate 35% of the time
It is important to keep in mind that the significant percentage of time these tests are inaccurate are tests conducted perfectly under ideal conditions. Many officers that conduct these tests have inadequate training and do not provide the detailed instructions that are required. When the officers do not give proper directions, conduct the FSTs according to the strict requirements, make sure that there are proper conditions (i.e. poor lighting, wet slippery surface) or score the test properly the false positive rate is much higher.
The final piece of evidence that is based on unreliable science is blood alcohol testing, which is typically breath testing. Courts across the U.S. have recognized that breath test results have a 20 percent margin of error. This margin for error means that someone who has a blood alcohol concentration BAC) below .08 percent may test above .08 percent. This margin of error assumes that the machine is properly maintained and calibrated.
The bottom line is that there is virtually no scientifically reliable evidence used in Pennsylvania DUI cases. The presumption of innocence means that the prosecutor has the considerable task of combining all of this scientifically vulnerable evidence and combining it to prove beyond a reasonable doubt that you were driving under the influence of alcohol. We frequently utilize scientific experts to provide evidence regarding the lack of reliability of the evidence submitted by the prosecution in a Pennsylvania DUI case.
For an effective DUI defense strategy, call us today at 412-475-9217 or toll free at (855) DUI-CRIME
Experienced Pittsburgh DUI lawyer Michael V. Worgul represents those accused of DUI. If you have been arrested in Pittsburgh or anywhere in Allegheny County, we are prepared to advise you of your rights and help you formulate the most effective DUI defense strategy so call us today at 412-475-9217.
