It’s a familiar scenario – the red and blue lights flash behind a vehicle, after pulling the vehicle off the road, the police officer asks the driver to submit to a series of tests to determine if he or she is intoxicated. The results of these tests can then be used as evidence of driving while intoxicated (DWI), a crime with potentially serious consequences, including imprisonment and losing your driver’s license. This procedure assumes that these so-called field sobriety tests and the breathalyzer are accurate, that they produce evidence that can be relied upon in court to support a conviction. But how accurate, how scientific are these tests, really? As it turns out, not very much, and it could result in an innocent driver being wrongfully convicted of a crime he or she didn’t commit.
Field Sobriety Tests
1. Unusual Circumstances: Field Sobriety Tests (FSTs) are conducted in unusual circumstances. FSTs are designed often involve unusual bodily movements or tasks that are somewhat difficult to perform. Additionally, the tests are often administered at unusual times (i.e. late at night) and under intense pressure. All of these circumstances add up and mean that FSTs are difficult to perform even when sober. A completely sober, innocent person could easily become nervous or simply find the unusual tests challenging and therefore “fail” the sobriety test.
2. The Government’s Own Research Show FSTs Are Unscientific: The three standard field sobriety tests are the horizontal gaze nystagmus, the walk and turn, and the one-leg stand. The National Highway Transportation Safety Administration conducted a study in which it showed:
○ Horizontal gaze nystagmus was accurate 77% of the time
○ Walk and turn was accurate 68% of the time
○ One-leg stand was accurate 65% of the time
So, assuming that the test was administered correctly and the police officer was unbiased, roughly one out of every four people to undergo the tests will fail even if that person is completely innocent.
Breathalyzers
1. Inherently Inaccurate: The readout of a breathalyzer is the blood alcohol content (BAC) of the person blowing into the breathalyzer. These readouts have long been assumed to be accurate; however, there are a number of recent studies that undermine this assumption. For example, one study determined that breath readings vary at least 15 percent from actual blood alcohol levels (Simpson, Accuracy and Precision of Breath-Alcohol Measurements for a Random Subject in the Postabsorptive State, 33(2) Clinical Chemistry 261 (1987)). As reported in 32(4) Journal of Forensic Sciences 1235 (1987), another study showed only 33 percent of breath test results correlated with corresponding blood tests.
2. Mechanical Errors: Breathalyzers are susceptible to hundreds of different problems. In order to know if the individual machine that was used in an individual case was defective one needs access to the testing police officer’s operation, the individual machine data, law enforcement crime lab procedures and calibration records, machine usage logs, and even video camera recordings of the testing room.
Conclusion
It is essential that anyone facing a DWI charge engage an experienced DWI attorney who is prepared to devote the time and skills necessary to reveal flaws. Often the flaws in the DWI field sobriety tests are most effectively argued by an attorney. Additionally, a DWI attorney will be able to reveal any flaws in police procedure or equipment through the pre-trial discovery process. If you find yourself facing DWI charges, it is highly recommended that you find a DWI attorney to fight on your behalf.
