The Imaginary Line in the Walk & Turn Test

One of the three field sobriety tests standardized by the National Highway Transportation Safety Administration (NHTSA) that police officers use when investigating a suspected drunk driver is the “walk and turn” test in which the subject is asked to walk nine steps along a straight line, turn, and walk back. Various factors can affect the accuracy of a test, and the NHSTA recognizes that it only correctly identifies someone as intoxicated roughly 70% of the time.

Even more troubling is the fact that police officers commonly issue the test incorrectly, requiring that the subject walk along an ‘imaginary’ line, without the visual guide of an actual line on the ground. This failure to properly issue the test as mandated by the NHTSA can result in a poorer grade that is inaccurate, and may incorrectly identify a suspect as intoxicated.

Real vs. Imaginary Line

In many cases where officers have judged a suspect to be intoxicated on the basis of a walk and turn test using an imaginary line, the officer will insist in court that the NHTSA manual does not require an actual line to be used in the test. This is categorically incorrect, and based around a misrepresentation of the handbook. In the instruction stage of the test, the officer is advised that they may demonstrate the test on an imaginary line, but the test itself requires the following conditions:

  • A designated straight line
  • A dry, hard, level, non-slippery surface.

Officers frequently quote the portion of the manual regarding demonstration in an effort to obscure the fact that they administered the simple test incorrectly.

Contact Us

If you have been charged with a DWI on the strength of a questionable field sobriety test, a skilled Dallas DWI attorney may be able to demonstrate that insufficient evidence exists for a conviction. Contact the Law Offices of Mark T. Lassiter today at (214) 845-7007 for a free consultation to discuss your case.


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