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DUI Investigation

DUI Investigation and Standard Field Sobriety Tests

By: Lain A Lawrence - DUI Defense Attorney Nov. 6, 2023

The standard field sobriety tests were developed in the late 1970’s. The tests were developed by the National Highway Traffic Safety Administration (“NHTSA”).  Testing was developed to improve the fatality rate on highways due to drunk driving.

The original studies yielded approximately 16 tests, but the NHTSA reduced these to three primary tests. These are the horizontal gaze nystagmus, the walk and turn, and the one-legged stand. Additional tests may be used by police officers.

SFST are considered “divided attention tests”. The primary function is to test a suspect’s ability to perform the type of mental and physical multitasking that is required to operate an automobile.

The tests are used uniformly by law enforcement agencies when a driver is suspected to be under the influence of drugs or alcohol. It is a sure bet that individuals suspected of driving under the influence will be requested to complete them. 

A skilled DUI attorney will need to understand what these tests. Police officers are often designated as an expert in conducting field sobriety tests. 

What is the Horizontal Gaze Nystagmus Test?

The first test that is typically administer by law enforcement is an eye test. Nystagmus is an involuntary jerking of the eyes. Depressants cause this jerking. A common depressant is alcohol

An officer will check for the three clues in each eye, which results in six possible clues. The clues are a lack of smooth pursuit, distinct and sustained nystagmus at the eye’s maximum deviation and nystagmus starting before the eye reaches 45 degrees.

If a person displays four or more clues, they fail the test.

Police will have the suspect stand feet together with their hands to the side. Police hold a stimulus, typically a pen, 12-15 inches from a person's nose. It must be slightly above eye level. 

Movement of the stimulus should take a maximum of two seconds to reach maximum deviation. The movement from one side of the face to the other should take four seconds. Officers will repeat this several times.

It is important to remember depressants cause nystagmus. Training manuals and material suggest that other drugs will not impact nystagmus. For example, marijuana will not cause nystagmus. This is important because most SFST are followed by a blood or breath tests, which can confirm the results.

What is the Walk and Turn Test?

They usually administer the walk and turn test as the second test. This test measures a defendant’s ability to maintain balance while performing a particular maneuver. 

To perform the test, a suspect will have to maintain a position and heel-to-toe position while the officer gives instructions. A defendant will then take nine heel-to-toe steps, turn, and take nine steps back. Turning requires the defendant to keep one foot on the ground.

An officer can observe the following clues:

1.      Can’t keep balance during instructions.

2.      Starts too soon.

3.      Stops walking.

4.      Misses heel-to-toe

5.      Steps offline

6.      Uses arms for balance.

7.      Improper turn

8.      Incorrect number of steps.

If a defendant shows two or more clues, they will be considered to have failed the test. Observers may notice certain clues at multiple points during the evaluation, but they still consider it as one clue. If a defendant misses one heel-to-toe step, we will consider it one clue. A defendant the misses every heel-to-toe

Mathematically there are some issues with this test. There are four clues that be detected at 18 points during the test. There are an additional 4 that can be exhibit at a single point. 

In total, there are approximately 76 points during the test that an officer can detect a clue. The NHSTA considers a defendant intoxicated if they perform 74 out of 76 (97% completion).

Again, the test does not provide any guidance as to its validity with respect to substances. The test procedures and interpretation are uniform for cocaine, alcohol, weed, or any substance.

What is the One Leg Stand test?

Law enforcement performs the one-legged stand test as the final test. This test requires a driver to stand on one leg for thirty seconds. The test is for balance, coordination, and ability to follow directions. 

The instructor will instruct the defendant to raise one leg of their choosing, 6 inches off the ground. They are then instructed to count to 30 out loud. An officer will observe the test and look for 4 potential clues.

An officer can observe the following clues:

1.      Sways while balancing

2.      Uses arms to balance.

3.      Hops up and down.

4.      Puts foot down.

2 out of 4 clues is considered a failure. A defendant receives only one clue regardless of how many times they perform an action, similar to the walk and turn. This means that even if they repeat the action multiple times, they will still only receive one clue. If a defendant puts their foot down 4-5 times, we will consider them to have one clue. 

This can lead to mathematically questionable results.

What are some common issues with SFST?

A major concern with these tests is their universal use for all substances. Officers will utilize them to test a defendant, regardless of the suspected basis for intoxication. A person under the influence of alcohol will be examined the same as a person under the influence of cocaine.

Also, a police officer gives the test if they think the person being tested is driving under the influence. Cops stop and ticket thousands of people daily, but SFST are only used during the course of a DUI investigation. 

Cops need a reason to think a person is drunk before asking them to do sobriety tests. This will rely on the defendant's observed driving, admissions of consumption, and any signs of intoxication. Typical signs of intoxication are blood shot eyes, smell of alcohol, or slurred speech.

This means an officer will have reason to believe a defendant is intoxicated prior to administering a test to determine if they are intoxicated. These tests cannot be equated to levels of intoxication under Colorado Law. Police are not permitted to say the test results would equate to a defendant with a BAC greater than .08. Instead, they must say a defendant did not perform them as a sober person would.

Always Speak with a DUI Attorney to Understand the Facts of your DUI Case.

While driving under the influence may seem like a minor charge, the impact on a defendant’s life can be significant. It is always advisable to speak with a DUI lawyer to understand the facts and possible defenses to your case.

Potential legal representation will offer free consultation to discuss the case with you. The Lawrence Law Firm routinely represents defendants charged with DUI’s in the Denver Metro Area.

We will gladly speak with you about the facts of your case and zealously represent you. Our goal is to provide aggressive and affordable representation to every client. We are willing to work with any budget, and we don’t want finances to prevent a defendant from fully protecting their rights.