Iowa DUI Lawyer: What are sobriety test clues?

The Iowa DUI standardized field sobriety tests, or, SFSTs, are a battery of divided attention and physical agility tests designed to discern whether a motorist at the roadside is impaired enough to warrant detention and further evidentiary testing for Operating While Intoxicated, or, OWI testing at the law enforcement center, jail, or station house. "Clues" are signs purportedly correlated to intoxication on those tests and thus points off on those tests.

Law enforcement officers may invoke implied consent if “reasonable grounds” to believe a motorist is operating a motor vehicle while impaired by alcohol, an illicit or prescription stimulant or depressant, or combination of all the above. Officers do not necessarily require probable cause to make an arrest to invoke implied consent and further detain the driver for sobriety testing. Reasonable grounds is akin to reasonable suspicion to believe a crime is occurring—defined by the United States Supreme Court as “more than a scintilla” of proof but “less than probable cause.”

The sum total grounds required to temporarily detain a drunk driving suspect in an Iowa DUI investigation contribute to these grounds and officers begin observation before they ever conduct a traffic stop—in Phase I of the investigation, called Vehicle in Motion.

Once a motorist is stopped—whether by their own volition or because an officer has activated emergency top lights and conducted a formal traffic stop—the officer is monitoring their behavior for telltale signs that the driver might be impaired. These signs include bloodshot, watery eyes, thick tongued or slurred speech, and the odor of alcohol coming from their person or the interior passenger compartment of the stopped motor vehicle.

Note that an officer need not conduct a traffic stop in order to interact with a motorist. The motorist might just as easily have stopped himself or herself, either to park before the officer arrived or at a gas station or convenience store. Counter intuitively, many clients and potential clients believe that an officer must conduct a traffic stop in order for a prosecution for drunk driving to be valid. That’s not true. A traffic stop may occur and, if it does, the officer must justify it with either reasonable suspicion or probable cause. However, it’s not a requirement for an investigation.

At some point, an Iowa DUI investigation leads to an officer directing the driver outside the vehicle and into their patrol car or in front of it. At this time, the officer will obtain consent from the motorist to perform standardized field sobriety tests. These tests are not pass-fail tests. They’re more nuanced than that. However, there is a score on each of these tests and a point off is considered a “clue” that contributes to a “decision point” whereby performance on the test will contribute to reasonable grounds for the officer to conclude impairment exists.

For example, on the Horizontal Gaze Nystagmus, or, HGN, the decision point is four “clues,” or, signs correlated to intoxication. They include failure to smoothly pursue the officer’s finger, pen, or flashlight within a 180 degree field of vision as well a distinct and sustained nystagmus, or, eye flutter, when focusing on that same finger, pen, or flashlight when it is stationary at four points in that same 180 degree field of vision: near 0, 45, 135, and near 180. These points are called “maximum deviation” for 0 and 180 and approximately 45 degrees before onset of maximum deviation right and left. Because it is technically—though not typically— possible for each eye to act independently, a point off for observed “clue” in each eye means that failure to smoothly pursue in both eyes is two points off and observed nystagmus at any given point during the test is also two points off. If the subject demonstrates four such points, the officer may use the HGN to contribute to sum total grounds to invoke implied consent.

Similarly, on the Walk and Turn, clues can include any number of possible missteps on the test, like a failure to maintain balance during the starting heel to toe position, starting too soon, missing heel to toe, stepping off the line, stopping entirely during the test, raising arms, taking the wrong number of steps, and improperly turning. Any two of these comprises a decision point where test performance can contribute to sum total reasonable grounds to conclude impairment.

On the One Leg Stand, clues include putting your foot down, raising your arms, hopping, and swaying.

If the officer believes they have reasonable grounds to conclude impairment following these three standardized tests, they may request a preliminary breath test that can itself contribute to such grounds. That is covered in a separate blog entry.

If you have been arrested for Operating While Intoxicated, or, OWI, Iowa’s version of what other states call DUI, please contact us for an initial consultation.