Chapter 5 DWI Lawyer Bob Keefer: DUI Guilt Myth


                                                                        CHAPTER 5

"THE GUILT MYTH"—FIELD SOBRIETY TESTS, SLURRED SPEECH AND ROADSIDE BREATH TESTS



There are a number of reasons that police officers give for arresting someone of a DUI. Three of the most common are a "failed" field sobriety test, slurred speech, and a breathalyzer reading above the legal limit. In this chapter we will examine each of these things in detail and show that, contrary to what is commonly assumed, they are far from infallible indicators of intoxication.



Field Sobriety Tests



Remember from the last chapter that by the time the officer has decided to ask you to perform a field sobriety test, he has probably already decided—consciously or unconsciously—to arrest you. At this point, the officer is already looking for evidence that you are intoxicated. As we all know, when we look for something—be it the car we are thinking about buying, a house for sale, or whatever else—we tend to find it everywhere. This is simply a fact of human psychology, and police officers are only human after all. However, this still introduces bias into a process that should be as objective as possible.

In spite of this bias, we would still hope that the officer has been trained to reliably interpret subjects' performance on the field sobriety tests. We would assume that police officers are proficient at determining whether a person is intoxicated by watching the subject perform an FST.

And this is precisely what most people think. Most people assume that if someone failed a FST according to a police officer's judgment, the person was almost certainly drunk. This assumption is understandable given the stereotypical scenario that most people have in their heads: a guy who, when asked to walk a line, wobbled along before falling flat on his face. Even if we concede that reality does not always fit the stereotype, we would still like to think that police officers should be able to tell—maybe not 100percent of the time, but at least most of the time—whether a person is drunk or not based on their performance.Unfortunately, this is just not the case. Two researchers from Clemson University decided to do an experiment to see how good police officers were at distinguishing someone who is under the legal limit from someone who is too drunk to drive, based entirely on watching them perform field sobriety tests.  Fourteen local police officers were shown videotapes of 21 subjects taking six common field sobriety tests and were asked to decide which were too intoxicated to drive." On average, the police officers determined that 46percent of the subjects were legally intoxicated.

So how did they do? Not well, considering that not a single subject had consumed alcohol. None. The blood alcohol level of every subject was .00percent! This is a particularly disquieting result considering that, if the officers and pulled these individuals over, they would have arrested an innocent person half of the time.

In addition to performing field sobriety tests, the subjects in this study also performed a number of "normal abilities" tests, including counting from 1 to 10, walking normally, and reciting personal information (such as their Social Security number, drivers license number, date of birth, home address and phone number). The police officers—who judged 46 percent of the subjects to be intoxicated from watching them perform FSTs—determined that only 15percent of the subjects were intoxicated when watching them perform these normal abilities tests. The moral of the story is this: compared to "normal" activities, field sobriety tests had the effect of making people appear drunk.

Okay, so police officers are not well trained on assessing the results of field sobriety tests. Would more training help? Can anybody make fairly reliable judgments based on field sobriety tests? Surely these tests have a sound basis in science.

Wrong again. Field sobriety tests have little to no scientific basis. Here is a quick history of the modern FST. In the late 1970s the federal government gave a grant to a research group called the Southern California Research Institute (SCRI) to come up with a procedure for administering field sobriety tests that was more reliable that the ones being used at the time. The tests that the group eventually came up with, by their own admission, were still far from perfect. The group's own data showed that roughly half of subjects tested would have been arrested, despite their BAC being under the legal limit. Unsatisfied with these results, the federal government gave SCRI another crack at it. In 1981 they came up with some better data. This time roughly 30 percent of subjects would have been falsely arrested.

In 1981, SCRI published a report claiming that the barely passable 32 percent false arrest rate has been brought down to a confidence-inspiring 9 percent. Is this because these tests have been refined and "standardized"? While this is certainly what they claim, a careful examination of the actual studies that yielded these results paints a very different picture. A few researchers obtained their data and experimental design through the Freedom of Information Act and made a startling discovery.4 What they found was that a large proportion of the subjects had blood alcohol levels so far over the legal limit that their performance on FSTs was nearly irrelevant. They suggest that this is what field sobriety tests are really only good for: identifying people with blood alcohol levels way over the legal limit.

While it might sound unfair or exaggerated, the legitimate scientific studies on field sobriety tests point towards an unsettling conclusion: field sobriety tests are not only unscientific and unreliable, but, in the way they are actually used in on the roads, are designed to make people fail.

You yourself may have been a victim of an officer's inability to interpret your performance on field sobriety tests, as well as the lack of sound science behind these tests. If you are fairly certain, or completely certain, that you were not driving with a BAC above the legal limit, but you still "failed" a battery of field sobriety tests, then this is precisely what happened to you. The best thing you can do is to find an attorney who knows the truth behind these tests.



Slurred Speech



There is also a good chance that, in addition showing that you "failed" field sobriety tests, the police report also notes that you were slurring your speech. Slurred speech is one of those commonly accepted indicators of intoxication. But is it really true? Is slurred speech a reliable indicator of intoxication?

Yes and no. "Yes" in the limited sense that intoxication is indeed a common cause of slurred speech. If someone has been drinking heavily, it is likely that it will affect the person's speaking fluency. And, yes, it goes the other way: if someone is heavily slurring his or her speech—and in the absence of a speech impediment or neurological disorder—the person has probably been drinking. Research has indeed shown that most people can differentiate between sober and intoxicated speech when listening to recordings of people talking.

However, this does not mean that it is possible to judge, with a high degree of reliability, that a person is above the legal limit simply based on listening to them talk. Drinking and driving, remember, is not against the law. What is against the law is to operate a vehicle with a certain blood alcohol content or while being significantly impaired. So let us put the question a different way. Can a person accurately distinguish between someone who is too drunk to drive versus someone who consumed alcohol but can nonetheless drive legally, all based on how they talk?

To that question the answer is decidedly "No." Studies have shown that even experts in speech analysis are not that much better than the average person, or the average police officer for that matter, at making this kind of judgment. It is true that both experts and non-experts can usually tell a person who has been drinking heavily from someone who has not, but neither can consistently determine the relative amount of alcohol a person has consumed.

The other problem with using speech as an indicator of intoxication is that alcohol is not the only thing that causes one to slur one's words. The most common of these other potential causes of slurred speech, and the most likely to lead a police officer to make an unfair assumption, is stress. Stress can have a host of different effects on speech, such as a higher pitch, stuttering, and, yes, slurring. And as we all know, being pulled over is always a stressful experience. When we are extremely preoccupied with saying the right thing—as we are when talking to a police officer—we often cannot seem to form a normal English sentence, much less speak eloquently.



The Roadside Breath Test



The portable breathalyzer, which is used on the roadside, as well as the somewhat more sophisticated breath-test machine at the police station, are both subject to error. For the most part, both of these devices have the same weakness because they both work the same basic way—by measuring the alcohol content of the breath and using this measurement to estimate the alcohol content of the blood.

One of the most important factors that influence the results of both of these tests is breathing pattern. One study showed that holding your breath for 30 seconds before blowing into the breathalyzer increases the result a whopping 15.7 percent. Hyperventilating for 20 seconds, on the other hand, decreases it by 10.6 percent.

Yet another way in which breathing pattern can affect the results of a breathalyzer test has to do with what part of the breath the machine is exposed to. In other words, different parts of the exhalation will give different blood alcohol readings. The first part of the breath, made up of air from the top of your lungs, has much less alcohol in it that the last part of the breath, which comes from the bottom of the lungs.

Unfortunately, many police officers, knowing this, give the subject instructions like "Blow hard! Keep going!" Following these instructions will insure that the machine is exposed to the alcohol-rich blood from the bottom of your lungs. It is staggering to consider how many falsely high breathalyzer results have been obtained—and how many people have been arrested as a result—because of these instructions and the device's potential for inaccuracy.

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