Field Sobriety Testing (SFSTs)

Standardized Field Sobriety Tests (SFSTs) and non-standardized testing are widely used by law enforcement officers to detect impairment caused by alcohol or drugs. While these tests are considered as a reliable tool to determine impairment, there are a number of issues associated with them that should not be overlooked. In this article, we will take a closer look at the problems and limitations of SFSTs and non-standardized testing. From reliability and validity, to administration and training, to admissibility in court, we will explore the potential issues that can impact the accuracy of these tests and the potential impact on a person’s DUI/DWI case.

As a criminal defense attorney, San Antonio-based Brad Thornton, Board Certified in criminal law and a former chief prosecutor, will provide valuable insight on these issues and help you understand the legal implications of SFSTs and non-standardized testing.

Standardized Field Sobriety Testing (SFSTs)

Standardized Field Sobriety Tests (SFSTs) were developed in the 1970s by the National Highway Traffic Safety Administration (NHTSA) in partnership with the International Association of Chiefs of Police (IACP) and the National Sheriffs’ Association (NSA).

The SFSTs were created as a way to standardize the field sobriety testing process and improve the ability of law enforcement officers to determine if a driver is impaired by alcohol or drugs. Prior to the development of the SFSTs, officers used a variety of different tests to make this determination, and there was no consistency in how the tests were administered or evaluated.

The Standardized Field Sobriety Tests (SFSTs) are a series of tests used by law enforcement officers to determine if a driver is impaired by alcohol or drugs. The SFST battery is made up of three tests: the horizontal gaze nystagmus (HGN) test, the walk-and-turn test, and the one-leg-stand test.

The Horizontal Gaze Nystagmus (HGN) Test: This test is used to measure the involuntary jerking of the eye that occurs when a person is under the influence of alcohol. The officer will ask the driver to follow a small object, such as a pen or a flashlight, with their eyes as it is moved horizontally. The officer will look for three clues of impairment: if the eye cannot follow a moving object smoothly, if the eye jerks at a certain angle, and if there is a distinct jerking of the eye as it is held at maximum deviation.

The Walk-and-Turn Test: This test is used to measure a person’s ability to divide their attention and follow instructions. The officer will ask the driver to take nine heel-to-toe steps in a straight line, turn around, and take nine heel-to-toe steps back. The officer will look for eight clues of impairment: if the driver loses balance during the instruction phase, if they start too soon, if they stop while walking, if they do not walk heel-to-toe, if they step off the line, if they use their arms to balance, if they turn improperly or if they take an incorrect number of steps.

The One-Leg-Stand Test: This test is also used to measure a person’s ability to divide their attention and follow instructions. The officer will ask the driver to stand on one foot and raise the other foot six inches off the ground, keeping their arms at their sides. The officer will ask the driver to count out loud, one thousand one, one thousand two, etc. The officer will look for four clues of impairment: if the driver sways while balancing, if they use their arms to balance, if they hop or if they put their foot down.

Non-Standardized Field Sobriety Testing

In addition to the Standardized Field Sobriety Tests (SFSTs), law enforcement officers may use a variety of non-standardized tests to detect impairment caused by alcohol or drugs. These tests are not part of the official SFST battery and may not have been validated through research.

The Alphabet Test: This test is used to measure a person’s ability to follow simple instructions and their cognitive function. The officer will ask the driver to recite the alphabet, either forwards or backwards, starting at a certain letter. The officer will look for slurred speech, an inability to complete the task, or an inability to start the task.

The Finger-to-Nose Test: This test is used to measure a person’s motor skills and coordination. The officer will ask the driver to touch the tip of their nose with their index finger, with their eyes closed or open. The officer will look for an inability to touch the nose, or an inability to touch the nose accurately.

The Finger Count Test: This test is used to measure a person’s cognitive function and ability to follow instructions. The officer will ask the driver to hold up a certain number of fingers and then count them. The officer will look for an inability to hold up the correct number of fingers, or an inability to count the fingers accurately.

The Rhomberg Balance Test: This test is used to measure a person’s ability to balance and their sense of time. The officer will ask the driver to stand with their feet together, eyes closed, and head tilted back. The officer will ask the driver to estimate when 30 seconds have passed. The officer will look for an inability to maintain balance, or an inability to estimate the time accurately.

Issues and Defenses to Field Sobriety Testing

Standardized Field Sobriety Tests (SFSTs) and non-standardized tests are widely used by law enforcement officers to detect impairment caused by alcohol or drugs. However, there are a number of problems and issues associated with these tests that should be considered.

Reliability and Validity: SFSTs have been validated through research, however, they are not always accurate in determining impairment. Factors such as a person’s age, weight, and physical condition can affect their performance on the tests, and even a sober person may have difficulty completing them correctly. Non-standardized tests may not have the same level of reliability and validity as the SFSTs and may not be considered as reliable as the SFSTs.

Administration and Training: In order for SFSTs and non-standardized tests to be reliable, they must be administered correctly. However, there have been instances where officers have not followed the proper procedures, which can lead to inaccurate results. Additionally, officers may not be properly trained in administering the SFSTs, which can also lead to errors.

Admissibility in Court: While SFSTs are widely used by law enforcement, they are not always admissible as evidence in court. The prosecution must be able to prove that the tests were administered correctly and that the results are reliable. This can be challenging, and the defense attorney may be able to argue that the SFSTs should not be considered as evidence. Non-standardized tests may also not be admissible in court as evidence.

Other Factors: Even if a person performs poorly on the SFSTs or non-standardized tests, it does not necessarily mean that they are impaired. Other factors, such as a person’s driving pattern or their behavior, must also be taken into consideration.

It’s important to note that these are general points and there are some nuances that can be argued in court, but as a criminal defense attorney, it’s important to be aware of these potential issues and limitations when building a defense for a client accused of driving while intoxicated (DWI) based on SFSTs or non-standardized test results.