Field Sobriety Tests: What They Mean in DUI Cases

Driving under the influence (DUI) is a serious charge that can have significant legal repercussions. When someone is suspected of DUI, law enforcement officers often employ field sobriety tests as an initial screening tool. These tests evaluate a person's balance, coordination, and ability to perform tasks simultaneously, which can be compromised under the influence of alcohol or drugs. Commonly used field sobriety tests include the horizontal gaze nystagmus (HGN), the walk-and-turn, and the one-leg stand.

Understanding these tests is crucial from a legal standpoint because their outcomes can heavily influence the case. They are often the first piece of evidence used to establish probable cause for an arrest. However, it's important to note that these tests are not foolproof. Medical conditions, nervousness, or poor weather conditions can affect performance and test results.

If you are facing DUI charges and have undergone field sobriety tests, having a defense attorney is vital. A lawyer can scrutinize the circumstances under which the tests were administered, challenge their accuracy, and question the interpretation of the results. Defense strategies may include demonstrating that the tests were improperly conducted or arguing that external factors influenced performance.

For anyone in Los Angeles facing such a situation, contactLessem, Newstat & Tooson, LLP by calling (800) 462-7160.

What Are Field Sobriety Tests?

Field sobriety tests are physical and cognitive evaluations law enforcement officials administer to determine whether a driver is under the influence of alcohol or drugs. These tests measure a person's ability to perform tasks that require divided attention, mirroring the skills needed for driving. Officers can gauge whether a driver's faculties are impaired by simultaneously assessing mental alertness and physical coordination.

The most common field sobriety tests are:

  • Horizontal gaze nystagmus (HGN). This test involves observing a driver’s eyes as they follow a slowly moving object like a pen or flashlight. The officer looks for involuntary jerking of the eye (nystagmus), which can be exaggerated by alcohol consumption or the use of certain drugs.
  • Walk-and-turn (WAT). In this test, the driver is instructed to take nine steps along a straight line, heel-to-toe, turn on one foot, and return similarly. This test evaluates the driver’s ability to follow directions, maintain balance, and complete the task without stopping.
  • One-leg stand (OLS). The driver must stand with one foot approximately six inches off the ground and count aloud until told to put the foot down. This test measures balance, coordination, and the ability to focus on a single task.

What Are Officers Assessing?

Law enforcement officers are trained to look for specific indicators that suggest impairment when conducting field sobriety tests. These indicators, or "clues," help officers make critical decisions about whether a driver may be under the influence of alcohol or drugs.

In the HGN test, officers watch for several key indicators:

  • Lack of smooth pursuit
  • Onset of nystagmus before 45 degrees

During the WAT, officers look for:

  • Starting too soon
  • Stopping while walking
  • Not touching heel to toe
  • Stepping off the line
  • Making an improper turn

For the OLS, clues of impairment include:

  • Swaying while balancing
  • Hopping
  • Putting the foot down

How Accurate Are the Standardized Field Sobriety Tests?

Studies, such as the San Diego Field Sobriety Test (SFST) validation study, have shed light on the effectiveness of these tests under controlled conditions. According to this study, the HGN test was 88% accurate in identifying impairment. The WAT test showed a 79% accuracy rate, while the OLS test was 83% accurate.

Several factors can influence the accuracy of field sobriety tests, potentially leading to false positives or negatives.

Key factors include:

  • Medical conditions
  • Uneven terrain
  • Footwear
  • Poor lighting

The variability in test conditions and individual capabilities calls into question the universal reliability of field sobriety tests. This understanding is crucial for those involved in DUI cases, as it highlights the potential defenses and arguments regarding the validity of FST results.

What Are the Implications of Failing FSTs?

Field sobriety tests serve as preliminary assessments for law enforcement to determine impairment and are pivotal in building a DUI case. The driver’s performance on these assessments can influence an officer's decision to conduct further chemical testing, such as breath, blood, or urine tests, which can more accurately measure blood alcohol content (BAC) levels.

The results from FSTs are also critical in establishing probable cause for an arrest. Law enforcement officers use these initial assessments to decide whether sufficient evidence suggests that a driver is operating a vehicle while impaired.

Notably, drivers should know that participation in field sobriety tests is not mandatory. Drivers can decline these tests without direct legal penalties, such as additional fines or charges. However, refusing to participate in FSTs does not guarantee a person will avoid arrest. Officers can still use other observations, such as the odor of alcohol, erratic driving behavior, and physical symptoms of intoxication (e.g., slurred speech or bloodshot eyes), as grounds to arrest a driver for DUI.

How Can a Defense Attorney Help?

A knowledgeable defense attorney can employ various methods to challenge DUI accusations. These methods may include questioning the validity of the FSTs based on the conditions under which they were administered, the officer's interpretation of the results, or your physical and medical conditions that could affect your performance.

For those needing legal representation in Los Angeles, please contact Lessem, Newstat & Tooson, LLP at (800) 462-7160.