Sobriety tests flawed?


Summary of false positives in NHTSA sobriety testing

In the 1970s and 1980s, the National Highway Traffic Safety Administration sought to standardize sobriety testing in the field with a battery of tests, including horizontal gaze nystagmus, walk and turn, and one leg stand. Now 20 years into the 21st century, are the SFSTs flawed by too many false positives? Under Iowa drunk driving law, once an officer has reasonable grounds to believe a test subject is intoxicated, the officer may request a preliminary breath test. At that point, refusal or test failure invokes implied consent and the motorist is required to either refuse or consent to a more accurate Datamaster DMT test back at the stationhouse.

When special interests effectively lobbied both the federal government and state legislatures for greater DUI enforcement in the 1990s and 2000s, the BrAC/BAC standards were lowered from .10 grams of ethanol per 210 L breath or .10 grams of ethanol per 100 mL blood, to .08 BraC/BAC.


However, law enforcement officers were not required to learn an entirely new set of SFSTs nor brand new criteria for detecting the lower per se consumption limits. Instead, NHTSA and law enforcement commissioned a study in San Diego, California, authored by Jack Stuster and Marcelline Burns and a private laboratory, Anacapa Sciences, Inc., in August 1998 to validate the current testing procedures with some minor adjustments.


The testing raises some questions. First— straight out of the gate—only 261 of the 273 cases involved the entire battery of field sobriety tests (HGN, WAT, OLS). Second, only 217 of the 273 stopped for DUI appear to have been arrested for DUI, or, approximately seventy-three percent. Stuster and Burns at 16. Third, 87.9 percent of the sample was male with only 12.1 percent female. Query whether any application of SFSTs to the females in the general population suffers from serious sampling error—and gender discrimination.

Fourth, it appears that of those who were arrested, the range of BAC was .138 to .150, hardly justifying the application of SFSTs to BACs between .08 and .10.

Fifth, even the San Diego study acknowledges that driving is a complex task and that impairment as to such complexity cannot be assessed at the roadside. Stuster and Burns at 20. Moreover, the SFSTs do not directly correlate to impairment instead, the study seeks to correlate SFST performance to BAC levels. Id.


And, finally, sixth, there were 24 false positives. In other words, in almost ten percent of cases, law enforcement estimated BACs of over .08 but BACs were lower.

Despite these anomalies, the study’s authors asserted confidently that SFSTs—a skillset over a half-century old— provide a “clear indication” of “accuracy.” This lore has been incorporated in judicial decision making much to the delight of the federal transportation agency which, along with special interests fueled by grief politics and legislative pandering to neoprohibitionists, has subsidized state law enforcement training with publication and instruction on the administration of standardized field sobriety tests.

If you or a loved one has been arrested for OWI (DUI) in the State of Iowa in 2020 and beyond, you owe it to yourself to become an informed legal consumer. Contact Cmelik OWI and Criminal Law PLC for a free initial consultation today.



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