Keeping FSTs Out of a Trial

Posted on April 23, 2025 in Uncategorized

Written by Neil Halttunen

I want to address a common issue that DWI practitioners are facing, trying to keep FSTs out of a trial. One way is to take the position that FSTs are scientific evidence and make the prosecutor lay scientific foundation which they rarely can do.

The HGN test was the result of several studies. See Generally Session 8 of the NHTSA 2023 Manual. According to NHTSA, the “HGN is the most reliable field sobriety test.” Session 7, Pg. 5 of the 2023 FST Manual. That “most reliable” quote can be helpful when you are defending a case in which no HGN is reported depending on the drug category suspected.

However, I have found it more successful to challenge the HGN at trial because to prosecutor is typically not prepared for a challenge mid trial. I have the luxury of State v. O’Key, 321 Or 285 (1995) where the Oregon Supreme Court decided that the HGN test is scientific evidence and therefor the state must make a foundational showing (scientific evidence factors like in Daubert or your State’s counterpart) to make the HGN admissible. I simply wait in trial for the prosecutor to begin asking the arresting officer about HGN and then segue to “How did Mr. Smith do on the HGN?” At that point, I simply object with something like “Objection, lack of foundation, State v. O’Key” and my objections have been sustained every time. I have yet to find a prosecutor that has the presence of mind to lay the foundation, and they simply move on after becoming flustered.

I recognize that I have a luxury in O’Key, and all of you may not, but you may have comparable precedent or be able to create it. You can also use the officers lack of compliance with proper procedures to block HGN using pre-trial motions if you can get your court to agree HGN is scientific evidence using the “use made of the technique” prong of Daubert or your State’s counterpart combined with “The Standardized elements included Standardized Administrative Procedures, Standardized Clues, and Standardized Criteria.” Session 8, Pg. 6 of the 2023 FST Manual. “It is necessary to emphasize this validation applies only when the tests are administered in the prescribed and standardized manner, the standardized clues are used to assess the subject’s performance, and the standardized criteria are employed to interpret that performance. If any one of the SFST elements is changed, the validity may be compromised.” Session 8, Pg. 12 of the 2023 FST Manual’ In other words, if the test was not administered in a standardized way, then the results cannot be reliable, and so the results cannot be admitted as scientific evidence.

Here in Oregon, the appellate courts have long held that the other two Standardized FSTs (walk & turn and one leg stand) were not scientific evidence. That changed in State v. Ortiz, 325 Or App 134 (2023) and I managed to keep FSTs out of one trial by waiting for a mid-trial objection using Ortiz. However, that holding was reversed in State v. Ortiz, 372 Or 658 (2024) based on a plain error issue and not because the question does not remain open as to the scientific nature of FSTs.

As of right now, there is not a definitive answer in Oregon, but I believe that you can use these cases as persuasive authority and help you make arguments in your cases to the effect that FSTs are in fact scientific evidence and prevent their admission. At the very least, preserve appellate issues that will hopefully lead to some defense friendly precedent in your state.

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