What is Phase Three of OWI (DUI) Detection in Iowa? 


Phase Three consists of three standardized field sobriety tests or, SFSTs, that were developed by the National Highway Traffic Safety Administration (NHTSA) and that are in use by officers throughout the United States plus a preliminary breath test, or, PBT. They must be administered in a standardized way every time in order to retain what little scientific value they purport to import to OWI suspicion. 

For example, the horizontal gaze nystagmus, or, HGN, must start with the left eye every time. And the scoring for each eye is to consider three phenomena that studies have correlated to intoxication, including lack of smooth pursuit, distinct nystagmus at an approximate 45 degree angle before the onset of maximum deviation, and distinct nystagmus at maximum deviation. In studies commissioned by the NHTSA, a decision point in the HGN is four so-called clues, or, signs of insobriety. Even then, the studies indicate the HGN is only 77% accurate. In other words, of those who showed four or more clues, 23% were not over the presumptive legal limit of .10 grams ethanol per 210 L breath at the time of their testing. You’ll note that the .10 limit has been reduced .08 BrAC/BAC in all 50 states. The research was conducted before the change. However, the NHTSA and law enforcement agencies who use this testing assert that they have “revalidated” the tests and that they are “accurate” to the reduced standard.

The HGN test is considered the gold standard and “the most reliable” of all of the SFSTs. The so-called “gold standard” provides only 77% reliability even by NHTSA's own admission.

The Walk and Turn, or, WAT, is typically the second SFST administered by an officer in the field. The Walk and Turn consists of an instruction/demonstration phase and the test phase. Some officers “con” test subjects into beginning the test early by refusing to tell the test subject that he or she must not begin until and unless instructed to do so. When a test subject attempts to follow along by mirroring the officer’s instructions and demonstrations, it’s considered a “clue,” or, sign of insobriety.

The test includes nine heel to toe steps, a turn consisting of a series of small steps, and a return set of nine steps, all while counting out loud, for example, “one-thousand-one,” and so forth.

In addition to the signs of insobriety cited in the instruction/demonstration phase, the officer looks for incorrect number of steps, stopping, and improper turn.

NHTSA has concluded that just two “clues,” or, signs of insobriety comprise a “decision point” on this test because those who showed two such signs during testing were shown to be over the presumptive legal limit of intoxication just 68% of the time. 

Phase Three of DUI Detection from the 2006 NHTSA DUI Detection Manual. Once an officer has made a decision to ask a motorist to step out of a car during a traffic stop, the motorist becomes a test subject. Everything they do and say now will be documented by the officer and, in some cases, recorded by wireless microphone, in-dash camera, and possibly body cameras. The officer will demonstrate and administer three standardized field sobriety tests, or, SFSTs, and request a Preliminary Breath Test, or, PBT, in the field to determine if reasonable grounds exist to believe that the test subject is intoxicated sufficient to invoke implied consent and request a more formalized, and, more reliable, Datamaster DMT, back at the stationhouse. Many, but not all, times, an officer will believe that he or she also has probable cause to make an arrest in the field-- even before he or she obtains a more reliable Datamaster DMT test result or refusal at the stationhouse.

Standardized Field Sobriety Tests​ in phase three, Officer Friendly administers standardized field sobriety tests, or, SFSTs, in a standardized way. Here, the National Highway Traffic Safety Administration instructs test administrators on the proper way to conduct the Horizontal Gaze Nystagmus, or, HGN, field sobriety test. 

Legislature has barred the admissibility of the test results—even as to the presence of alcohol—before the jury. However, if a test subject refuses a PBT, the invocation of implied consent—detention and the hard choice of refusing or consenting to the Datamaster DMT back at the stationhouse is virtually assured.

Next, we’ll discuss transport to the sally port and the implied consent advisory.   

If you or a loved one has been arrested for OWI (DUI) in Iowa, contact DAC-LAW PLC, 305 2nd Avenue, Suite 200, Cedar Rapids, Iowa, at 319-389-4276, 

The final SFST is the One Leg Stand, or, OLS. The One Leg Stand is just what it says. The officer demonstrates the test and then asks a test subject to raise his or her foot, six inches off the ground, with the sole of their shoe, or, their foot parallel to the ground, and hold it there while counting “one-one-thousand” and so on until advised to stop. The officer will generally allow this test to continue until the test subject demonstrates two or more clues, or, signs of insobriety including: uses arms to balance, sways, hops, and/or puts their foot down. Sometimes they stop the test for “safety reasons” but I find this is exaggerated to bolster the OWI arrest. The test is typically no longer than 30 seconds in three distinct scoring phases.

Ultimately, the test adminstrator will seek a preliminary breath test (PBT) if he or she believes that, following SFSTs, “reasonable grounds” exist to believe that the test subject is intoxicated. A preliminary breath test is sometimes confused with the Datamaster DMT because both require breath samples. The PBT is akin to an SFST because it is a breath test administered in the field. The results of the PBT are so inherently unreliable that the Iowa