Navigating the Nuances of Sobriety Testing: A DWI Lawyer's Guide

Understanding the Standardized Field Sobriety Test

The Standardized Field Sobriety Test (SFST) is a battery of three tests used by law enforcement to help determine whether a driver is impaired. The National Highway Traffic Safety Administration (NHTSA) has standardized these tests to provide a consistent method for evaluating impairment. However, the effectiveness and accuracy of these tests can be influenced by a variety of factors, making the role of a DWI lawyer critical in interpreting and challenging the results.

Horizontal Gaze Nystagmus (HGN)

The Horizontal Gaze Nystagmus (HGN) test is designed to observe the involuntary jerking of the eyes as they follow a moving object, such as a pen or flashlight, to the side. Officers look for three indicators of impairment in each eye: if the eye cannot follow the object smoothly, if jerking is distinct when the eye is at maximum deviation, and if the angle at which jerking begins is within 45 degrees of center. According to research, the HGN test is relatively reliable, with studies by the NHTSA suggesting it accurately identifies impairment in 77-88% of individuals. However, environmental factors, medical conditions, and officer error can affect the results.

Walk and Turn (WAT)

The Walk and Turn test requires a suspect to walk nine steps heel-to-toe along a straight line, turn on one foot, and return in the same manner. This test assesses balance, coordination, and the ability to follow instructions. The NHTSA claims this test has an accuracy rate of 68% when used in conjunction with the HGN. However, the subjective nature of what constitutes "sufficient" performance, along with factors such as uneven terrain and footwear, can impact the results.

One Leg Stand (OLS)

In the One Leg Stand test, the individual must stand with one foot approximately six inches off the ground and count aloud by thousands until told to stop, usually for 30 seconds. This test is designed to measure balance and attention. The NHTSA reports a 65% accuracy rate for this test. However, like the WAT, it is not a common daily activity, and factors such as age, physical condition, and nervousness can influence performance.

Challenging Sobriety Test Results

A DWI lawyer's role is to scrutinize the administration and interpretation of these tests. They may question:

• The training and qualifications of the officer conducting the tests.
• The conditions under which the tests were administered, including lighting, weather, and road conditions.
• The subject's medical history or physical limitations that could affect test performance.
• The presence or absence of video evidence to corroborate the officer's observations.

The Importance of Video Evidence

Video evidence can play a crucial role in DUI/DWI cases. It provides an objective record of the SFST and can be used to support or refute the officer's testimony. The absence of video evidence can be a significant point of contention, as it leaves the interpretation of the test results solely to the officer's discretion.

Conclusion

The SFST is a complex tool that requires careful analysis. A DWI lawyer with a thorough understanding of these tests can effectively challenge their validity and reliability. Given the potential for subjective interpretation and the impact of external factors, the expertise of a DWI lawyer can be the difference between conviction and acquittal.

For more detailed information on the SFST and its effectiveness, you can visit the National Highway Traffic Safety Administration or consult the American Bar Association for resources on legal representation in DUI/DWI cases.