Understanding Common CHP DUI Field Sobriety Tests

Operating a vehicle while intoxicated is considered a serious crime in the state of California. Law enforcement officers, particularly those with the California Highway Patrol (CHP), rely on field sobriety tests (FSTs) to determine whether a driver is impaired. These tests are often administered roadside after a traffic stop and can significantly impact the outcome of a DUI case. Understanding these tests can be crucial, especially if you’re facing charges and need the support of a San Diego criminal defense attorney.

What Are Field Sobriety Tests?

Field Sobriety Tests (FSTs) are a series of physical and cognitive exercises used by law enforcement officers to evaluate a driver’s coordination, balance, attention, and ability to follow directions. The results help the officer determine whether there’s probable cause to make a DUI arrest.

While FSTs are standardized by the National Highway Traffic Safety Administration (NHTSA), the way they are administered and interpreted can vary, which is why a criminal defense attorney is essential when challenging DUI allegations.

The Three Standardized Field Sobriety Tests

The CHP typically uses three standardized tests:

1. Horizontal Gaze Nystagmus (HGN) Test

This test examines the involuntary jerking of the eye, known as nystagmus. The officer will ask the driver to follow an object, such as a pen or flashlight, with their eyes. Signs of impairment include:

• The eye makes an involuntary twitch when moving sideways.
• Jerking occurring before the eye reaches a 45-degree angle
• Lack of smooth pursuit

While this test may appear simple, it requires careful observation and proper technique. Many factors can affect the results, including fatigue, medical conditions, or even flashing lights from passing vehicles. A skilled criminal defense attorney in San Diego can question the accuracy of the test during court proceedings.

2. Walk-and-Turn (WAT) Test

During this coordination-based test, the officer tells the driver to take nine heel-to-toe steps in a straight line, pivot on one foot, and walk back the same way. Indicators of impairment include:

• Struggling to stay balanced while receiving instructions
• Starting before instructions are complete
• Incorrect number of steps
• Stepping off the line

Although the Walk-and-Turn test is frequently administered, it is not entirely reliable. Uneven pavement, poor lighting, nervousness, or physical limitations can result in poor performance. If you failed this test, a criminal defense attorney can help present mitigating factors in your defense.

3. One-Leg Stand (OLS) Test

The individual is instructed to balance on one leg and count out loud until the officer signals to stop. Typically, the officer times 30 seconds. Signs of impairment include:

• Swaying while balancing
• Using arms for balance
• Hopping or putting the foot down

This test also demands both physical control and mental focus, which not everyone possesses under pressure. If you have balance issues or suffer from anxiety, your results may be misleading. A knowledgeable DUI lawyer in San Diego can use these factors to argue against the reliability of your test performance.

Non-Standardized Field Sobriety Tests

CHP officers may also use non-standardized FSTs such as:

• Finger-to-nose test
• Reciting the alphabet
• Counting backwards
• Touching fingertips together

Although these are not officially recognized by the NHTSA, they are sometimes used to supplement observations. These tests are even more subjective and can be easily challenged by a competent San Diego criminal defense attorney.

Are You Obligated to Take a Field Sobriety Test in California?

Many people are surprised to learn that field sobriety tests are voluntary in California. You are not legally required to participate in these tests. However, officers are not obligated to inform you of this fact. Politely refusing may help protect your rights without incriminating yourself.

It’s crucial to distinguish between field sobriety tests and chemical testing methods like breath, blood, or urine samples. While you can refuse an FST without penalty, refusing a chemical test after a lawful arrest can result in license suspension and other consequences.

If you were unsure of your rights during a traffic stop, it’s critical to speak with a defense attorney in San Diego to review your case and explore your legal options.

How CHP Officers Evaluate FST Results?

CHP officers are trained to look for “clues” of intoxication in each test. The presence of two or more clues in a given test may result in an arrest for DUI. These clues are documented in the officer’s report and often used as evidence in court.

Unfortunately, these evaluations are highly subjective, and mistakes or biases can play a major role. Officers may fail to consider medical conditions, age, or even footwear that could influence test results. A well-prepared San Diego criminal defense attorney can scrutinize the administration and interpretation of these tests to weaken the prosecution’s case.

Challenging FST Evidence in Court

If you’ve been charged with DUI based on FST performance, don’t assume the case is airtight. A DUI attorney in San Diego can challenge the legality of the stop, the officer’s training and conduct, and the accuracy of the tests.

Some common defense strategies include:

• Arguing the test was administered improperly
• Highlighting environmental or physical conditions that impacted performance
• Disputing the officer’s credibility or observations
• Demonstrating that poor performance was due to unrelated health or stress issues

Why You Need a San Diego Criminal Defense Attorney?

Being charged with a DUI can be overwhelming and may significantly impact your future. FST results can heavily influence whether charges are filed or dropped. That’s why working with a defense attorney is crucial from the moment you’re arrested.

An experienced lawyer can:

• Investigate whether CHP officers followed proper protocol
• Dispute the accuracy and reliability of field sobriety test outcomes
• Advocate on your behalf in court using a well-prepared legal defense
• Work to get the charges minimized or entirely dropped when possible

Your freedom, license, and reputation are all on the line in a DUI case. Having experienced legal counsel greatly increases your chances of a favorable outcome.

Field sobriety tests are widely used by the California Highway Patrol to detect impaired drivers, but they are far from flawless. These tests are influenced by numerous subjective and environmental factors, and they can be challenged effectively with the help of a San Diego criminal defense attorney.

If you or someone you know has been arrested for DUI, don’t delay—consult with a criminal defense attorney or a DUI lawyer in San Diego to understand your rights, review the evidence, and mount a strong legal defense. Choosing the right lawyer can significantly influence the result of your case. Trust your defense to someone with a proven track record—Vikas Bajaj, a San Diego criminal defense attorney brings experience, dedication, and aggressive representation to every DUI case. When your future is on the line, choose Vikas Bajaj for the legal defense you deserve.