Category Archives: Field Sobriety Tests

Nystagmus: “The Eye Test”

You may have heard of the "eye test" in DUI investigations.  This is the nystagmus field sobriety test or, more accurately (there are 47 different kinds of nystagmus),  the horizontal gaze nystagmus test.  It is one of the most commonly used field sobriety tests, as it is one of three which make up the federally-approved "standardized battery" of tests, or SFSTs.

The test is essentially a measurement of the movement of the eye.  Simply stated, "nystagmus" refers to a distinctive involuntary jerking of the eyes; horizontal gaze nystagmus is a pendular (back and forth) movement.  This type of nystagmus is commonly measured by the officer in three three different ways, each time using an object such as a pencil, penlight or finger placed a foot or so in front of the suspect’s nose and moving it slowly to the left and then to the right.

The first part of the test is to determine the angle of onset of nystagmus — that is, the angle at which the moving eye begins the jerking motion.  The suspect looks straight ahead and, without moving his head, moves his eyes slowly to the right or left.  The officer is supposedly able to detect when the nystagmus begins and is supposedly able to estimate the angle from straight ahead at the point where it begins.  If the onset is prior to 45 degrees, in theory, the blood alcohol level will be over .05%.

The second part of the test is to note whether the jerking becomes more "distinct" when the eye is moved to the lateral extreme — that is, when there is no longer any white of the eye visible at the outside of the eye.

The third part is to determine whether there is a lack of smooth pursuit: rather than following a moving object smoothly from the beginning, the eye jumps or "tugs".

Under federal standards, the officer is supposed to use an objective scoring criteria for each of the three tests, and the total score determines whether the supect passed or failed. 

In reality, few officers understand the test, administer it correctly, or use objective scoring.  Many simply report that they "detected the presence of nystagmus", and subjectively count that as a failure.  It is, however, the characteristics of nystagmus, not the simple presence,  which is relevant to determining possible impairment.  And, unfortunately, many things cause nystagmus and some of us have it under normal conditions.

More on nystagmus next week….

Supreme Court OKs Forced Blood — After 3 Breath Tests

On January 18, 2005, the U.S. Supreme Court declined to review a state supreme court case endorsing the nonconsensual extraction of a blood sample from a DUI suspect — after he had already consented to three earlier breath tests. On February 19, 2002, police in Wisconsin pulled over Jacob Faust as he left a bar. Faust admitted that he had five brandies and failed the field sobriety tests. He voluntarily submitted to a roadside breath test; the results indicated a blood-alcohol concentration of .13% — well above Wisconsin’s .08% legal limit. He was arrested and, at the police station, agreed to take another breath test. Two separate tests on the breathalyzer indicated BACs of .09%. The officer then asked Faust to submit to the withdrawal of a blood sample.

Having already taken three breath tests, Faust finally refused further testing. He was immediately served with a notice of license suspension for refusing and taken to a hospital where a blood sample was drawn. The result of the blood test was .10%, almost the same as at the station. At a suppression hearing, the officer admitted it was not departmental policy to demand further tests and he did not suspect the use of drugs: he simply wanted "additional evidence" because Faust was only .01% over the limit. The trial court granted the motion to suppress, and the Court of Appeals affiirmed:

"Once an individual arrested on probable cause for OWI has provided a satisfactory and useable chemical test, the exigent circumstances justifying a warrantless and nonconsensual blood draw no longer exists."

In a 4-3 decision, the Wisconsin Supreme Court reversed, holding that "(t)he nature of the evidence sought — that is, the rapid dissipation of alcohol from the bloodstream — not the existence of other evidence, determines the exigency." (Of course, by this reasoning the police can take as many chemical tests — 15 or 20 — as they want; there is almost no limit since alcohol will continue to dissipate for hours.) Amazingly, the Court further found that the police had a right to additional tests since they can’t predict whether a breath test will be found reliable in court. (In a footnote (fn28), the Wisconsin Supreme Court may have noted the real reason for this blatantly dishonest opinion: "There were 292 people killed and 6,570 injured as a result of alcohol-related motor vehicle crashes in Wisconsin during the year 2002…" In other words, the ends justify the means — the Constitution notwithstanding.) One of the three dissenting justices observed:

Without consent, without a warrant, and without exigent circumstances, the forced blood test in the present case violated the United States Constitution… The majority’s argument is essentially that because law enforcement officers do not know what will happen at trial (and no one does, of course), it was reasonable for them to take as many valid tests of the suspect’s blood alcohol as they thought necessary to sustain a conviction."

The U.S. Supreme Court denied a writ of certiorari (refused to hear the case). Wisconsin v. Faust, #04-471. Police are now apparently constitutionally free to give blood-alcohol tests as many times as they wish.

DUI, Field Sobriety Tests and “Circadian Rhythm”

Most drunk driving arrests take place at night, often after midnight. One reason for this is that many police officers engage in "cherry picking" — that is, the illegal practice of staking out bars and restaurants from about 10:00am to "closing time", pulling cars over on some pretext as patrons leave and drive away. It is during this period of time that the individual’s circadian rhythm is taking effect. The circadian rhythm is that 24-hour biological alarm clock in each of our bodies, most noticeable when we experience "jet lag".

Researchers have found that individuals will perform more poorly in tests during the low point of the circadian rhythm — that is, during the hours after midnight and into the early morning. It is just such tests — called "field sobriety tests" — that officers use to determine whether a driver is intoxicated or not. Specifically, British physicians and psychiatrists reported that "the same blood alcohol level is associated with a significantly greater impairment of different aspects of psychological funtioning when achieved in the morning." "Circadian Variation in Effects of Ethanol in Man", 18 (Supp. 1) Pharmacology, Biochemistry and Behavior 555. The researchers concluded that "the differences we have found…must be attributable to circadian change and susceptibility of the body to its effect."