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Standardized Field Sobriety Tests

When a traffic police officer stops you on suspicion of impairment on the road, you will be asked to undertake field sobriety tests (FST). These field exercises are meant to determine impairment, paving the way for chemical tests that determine the level of impairment. When you are subjected to these exercises, the officer sees how well you can coordinate, balance, and your attentiveness on the road. Field sobriety tests are not a legal requirement for persons not serving probation for a DUI offense or underage. This means your refusal to submit to them will not result in legal consequences, but it does not stop an officer from arresting you on DUI suspicion. If you are arrested for DUI in Los Angeles, get in touch with us at Jonathan Franklin DUI Attorney to help you fight the charges leveled against you.

Understanding Field Sobriety Tests

Before an officer pulls you over, they must have a reasonable cause for it. If your driving pattern or behavior on the road suggests intoxication, an officer will stop you. They will further order you to field sobriety tests to establish if you are impaired or not. Unfortunately, these tests are not completely accurate, resulting in many individuals getting arrested for failing them.

In most cases, if you fail these tests, you will be arrested for drunk driving. However, charges for the offense will not be immediately brought against you until further chemical tests are carried out. These chemical tests are more accurate and indicate your intoxication level. If the chemical tests show a significant level of intoxication, you will get charged with a DUI offense where your failed field sobriety tests will also be used.

In California, you don’t need to be subject to FSTs. You can refuse to participate in these tests without legal consequences. But, this doesn’t stop the officer from arresting you for further investigation into your intoxication.

In many instances, an officer may try to manipulate you into submitting to FSTs. Whether you agree to them or not, if an officer has decided to apprehend you for a DUI, they will.

The inaccuracy of FSTs has seen many people fail the tests even when they are not intoxicated by drugs or alcohol. Failing a test may see you faced with biased and unfair treatment, especially when you display impairment. You can fail FSTs because of:

  • Medical Issues - You could be having a medical issue affecting your speech, coordination, or balance. These symptoms are similar to those of an impaired person. When you fail the sobriety tests because of this, it could be assumed that you are intoxicated.
  • Environmental conditions – Depending on when the test is carried out, the present weather can affect your performance.
  • Your age – If you are more advanced in age, your balance may be less than that of a younger driver.
  • Weight – How heavy you are as likely to affect your balance. For instance, if you are subjected to a one-leg stand and are obese, you will be unlikely to maintain balance.
  • Dressing – The clothes and shoes you are wearing at the time of the test can result in you failing the test. Persons with tight clothing or uncomfortable shoes or high shows will not perform as well as persons with more comfortable shoes and clothes.
  • Noise and incorrect instructions – Typically, FSTs are carried out on the roadside. The noise from moving vehicles can result in poor understanding of the instructions given. As a result, you may fail in the tests, and you get arrested for intoxicated driving.

When Must You Agree to FSTs?

Earlier, we indicated that you could decline from taking these tests, and you face no legal repercussions for your decision. However, certain situations will mean you must agree to these tests when asked to. Drivers under 21 years must agree to the tests if stopped on impaired driving suspicion. This means if, in this age bracket, you have no option of declining the test. A refusal when you are below 21 years will enhance the penalties you receive upon conviction.

You cannot refuse to field sobriety tests if you are currently on probation for a DUI offense. If you decline the tests under these circumstances, it will mean you are guilty of drunk driving. This realization can lead to the termination of the probation, and the judge sentencing you to jail instead.

Standardized Field Sobriety Tests

Multiple tests to evaluate your sobriety or impairment on the road exist, but not all are approved or standardized by the National Highway Traffic Safety Administration (NHTSA). This government agency is tasked with ensuring road safety and issues the police’s necessary protocols to guide them when carrying out FSTs.

The standardized FSTs by the NHTSA are three, and they are:

  • The one-leg stand test (OLS)
  • Horizontal gaze nystagmus test (HGN) and
  • Walk and Turn test (WAT)

Although there are many other types of field sobriety tests, these are the standardized ones because they are considerably more reliable when administered correctly.

How the NHTSA Validated the Tests

Research facilitated by the NHTSA was conducted through the San Diego police department in 2018. The research involved various types of field tests, with only the three discussed above showing better reliability than their results and impairment. However, the tests are entirely not accurate, with some errors in each.

The Horizontal Gaze Nystagmus Test (HGN)

This test involves gazing at an item that the officer moves horizontally with you moving your eyes horizontally as the item moves. During this test, the police officer looks for the involuntary jerking of your eyes from one end towards the other instead of a steady and slow movement as the object moves. Typically, you would not be aware that your eyes are jerking, reaching the conclusion of impairment. This jerking of the eyes involuntarily is known as nystagmus.

Various kinds of nystagmus exist, but not all are associated with alcohol impairment. As you move your pupils and you are impaired, there is a specific angle the officer will be looking for. If your eyes’ jerking begins early before arriving at an angle of 45 degrees, the officer will conclude you are significantly impaired.

This test, according to the NHTSA, is 88% valid. This is an indication that you are operating your vehicle with a BAC of 0.08% or higher.

Walk and Turn Test (WAT)

The test is designed to test the attentiveness of a driver. When this test is administered to you, you will be required to be attentive to both mental and physical tasks simultaneously. This test is also known in different names that include:

  • Nine step test
  • DUI walk the line test
  • Nine step walk and turn test
  • DUI straight-line test

The NHTSA believes that if you fail this test, there is a 79% chance that your BAC level is 0.08% and over. During the test, you must remember every instruction issued because they carry a physical movement like:

  • Taking nine steps with each step touching your heels to your toes while maintaining an imaginary straight line.
  • Turning and
  • Taking another nine steps back to where you started

As you take the test, the officer is watchful for impairment signs that include:

  • Determining if you can maintain your balance as you are instructed on new tasks
  • If you immediately begin your walking
  • If you stop as you walk
  • If you find it challenging to touch your heel to your toes
  • If you are unable to keep a straight line
  • If you use your hands to stay balanced
  • If after making the steps you are instructed to, you can make a turn back
  • If you follow the instructions on the steps to take

Should you display any of the signs above, the officer can conclude you are impaired and arrest you for further investigation.

One Leg Stand Test (OLS)

This test is also designed to determine your attentiveness. You will receive instructions from the officer as you perform another task. The officer administers the test as they instruct you to:

  • Lift your foot up the ground for about six inches
  • Keep your current position where your leg is lifted up
  • Audibly count starting at 1001 until 1030
  • Turn your head towards your foot

As you do the test, the officer is looking for the following signs that will indicate impairment:

  • If you sway from in different directions
  • If you need your hands to keep balance
  • If you can stand still or you hop
  • If you keep your foot up as you finish counting

The NHTSA rates the accuracy of this test at 83%. This means, if you fail the test, you are probably driving with a BAC of 0.08% or over.

Conditions Affecting FSTs Accuracy

FSTs are not entirely accurate in determining intoxication or impairment. The accuracy levels are challenged by many conditions, both environmental and personal. Because of these conditions, when you fail in any tests, it is quickly and often concluded that you are impaired.

However, the standardized field sobriety tests are to be carried out in a favorable and safe environment according to NHTSA to enhance their accuracy. If you are charged with a DUI, your lawyer can challenge your conclusion that you were impaired by stating that other factors influenced your failure to the tests. The jury must also be convinced that the tests were fairly carried out before concluding impairment. The various conditions that interfere with the accuracy of field sobriety tests are:

Poor Lighting

When an officer stops you at night on suspicion of drunk driving, they should ensure you take the test in a well-lit location. You must be able to see your surroundings well, and the officer giving the instructions. If the place has insufficient lighting, the officer can use a flashlight. Poor lighting affects the test accuracy because you would not see where you are as you perform the tests. For instance, if you are asked to take nine steps and turn if you don’t see, there is a stone on your path, you can trip and fall. This can be concluded as a failure to the test erroneously.

Suitable Ground

The ground where you stand to perform the tests contributes significantly to your passing or failing the sobriety test. The ideal ground should be well leveled, dry, hard, and not slippery. Also, sufficient space is necessary if you are to perform the test well. If the location does not meet these conditions, an officer can move you to a better place that will not interfere with the test’s accuracy.


Noise from the surrounding can affect audibility. If the area is noisy or many moving vehicles make it difficult for you to hear instructions conveyed by the officer, you are likely to fail in your test. The officer, while administering the rest, must ensure there is no interference by noise. If you don’t hear well, you will do the wrong thing, leading to your failing the test.

Crucial Defense Strategies that your DUI Attorney Can Use

Your performance during the field sobriety tests administering is often used as evidence of your intoxicated driving in court. The failure is seriously considered when convicting you of a DUI offense, but a skilled attorney can challenge these results. Some arguments your lawyer will present include:

  • Arguing that you were not in a suitable mental or physical condition to take the tests. If you were sick, old, have a problem with your back or legs, are obese, in pain, or have hearing challenges, you can fail the test. You may also have an underlying mental condition that would cause you to fail. All these can be presented to discredit the results presented.
  • If the officer kept moving from one place to another, they distracted you from performing the test well.
  • Your lawyer can argue that the clothing you had on was not suitable for carrying out the test. If you had ill-fitting shoes or uncomfortable clothing, it is difficult to perform the tests accurately.
  • Environmental conditions, as earlier discussed, can affect the accuracy of the results. Your lawyer can argue the ground was wet, soft, or not leveled if that was the case or the noise around was distracting. When any of these is applicable, it is likely to fail the test.

Find a DUI Lawyer Near Me

Failed field sobriety tests have seen many people wrongly accused of intoxicated driving. The penalties you would receive and other consequences adversely affect you in various ways. Fortunately, a skilled attorney can challenge the results from the field sobriety tests used to strengthen the case against you. At Jonathan Franklin DUI Attorney, we understand the mistakes involved in FSTs that lead to a conviction on a DUI offense. With this understanding, we passionately challenge the prosecutor’s case to get you a desirable outcome. If you are arrested for a DUI in Los Angeles, call us at 323-464-6700 to talk about your case in detail.

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Jonathan Franklin DUI Attorney
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