Field Sobriety Tests

What are Field Sobriety Tests?

Field sobriety tests are often divided attention tests (think rub your stomach while patting your head). Although they are not scientific tests, law enforcement uses them to obtain evidence of driving under the influence. The results of the tests are used by prosecutors to convict drunk drivers and to justify DUI arrests.

Refusing Field Sobriety Tests

You may refuse to do any field sobriety tests. One exception to this is that you must provide a blood, breath, or urine sample. However, you are only required to provide a sample if law enforcement arrests you for driving under the influence. Failure to provide a sample can result in further consequences.


“Standardized” Field Sobriety Tests

The following three tests are approved for law enforcement use by the National Highway Traffic Safety Administration.


Horizontal Gaze Nystagmus

field sobriety tests

Horizontal Gaze Nystagmus is an involuntary jerking of the eye that happens when the eyes move to the side from center point. Prior to the administration of this test, an officer must check a subject’s eyes for equal pupil size, resting Nystagmus and equal tracking. The officer administers the test by slowly moving his finger in front of the suspect’s eyes.

An officer administering this test will check for three clues in each eye while checking for HGN:

  • Lack of Smooth Pursuit. When the eyes jerk or bounce as they follow a smoothly moving stimulus.
  • Distinct and Sustained Nystagmus at Maximum Deviation. When the eye jerks when it remains to the side for a minimum of four seconds.
  • Onset of Nystagmus Prior to 45 Degrees. When the eye begins to jerk when it moves 45 degrees from the center.

Four or more cues indicates that the suspect probably has a blood alcohol level over .08%.


Walk and Turn (aka “Walking the Line”)

field sobriety tests

The walk and turn test is a divided attention test. It divides the suspect’s attention between physical and mental tasks. The physical task is balancing and walking on a line. The mental task is completing the test exactly as instructed. The test begins with the instruction phase, followed by the walking stage.


The instruction phase begins with the suspect standing with their feet heel to toe (right foot behind) and arms at their sides. The suspect remains in this position while the officer explains the test. Next, the officer demonstrates three heel-to-toe steps, a turn, and three heel-to-toe return steps.

For the performance part of the test, the suspect must keep their arms at their sides and take nine heel-to-toe steps, followed by a turn and nine heel-to-toe return steps. The suspect must walk a straight line and cannot pause once they start walking. While walking, the must keep their arms at their side, look down at their feet and count each step.

During the test the officer will look for a number of cues for this test, including:

  • Loses balance during instructions;
  • Starts walking too soon;
  • Stops while walking;
  • Fails to touch heel-to-toe;
  • Steps off the line;
  • Uses arms for balance;
  • Makes an improper turn;
  • Takes the wrong amount of steps.

If the officer observes two or more of these cues, it indicates the suspect probably has a BAC over .08%.


One Leg Stand

one leg stand

There are two stages to the one-leg stand test. First the officer instructs the suspect in how to perform the test. Second, the suspect performs the test. During the instruction phase, the officer will provide oral instructions on performing the test. The officer will also demonstrate part of the test. Once this is complete, the officer asks the suspect if they understand the instructions.

During the performance stage, the suspect raises one leg with their foot parallel and approximately six inches off of the ground. With their hands to the side, they count in thousands (one-one thousand, two-one thousand, etc.) while looking at their foot until instructed to stop.

During the test, the officer will look for six possible clues: swaying, using arms for balance, hopping or putting your foot down. If the officer observes two or more clues, it indicates that the suspect probably has a BAC over .08%.


Other Field Sobriety Tests

Law enforcement commonly uses other field sobriety tests including:


Modified Romberg

rhomberg

Moritz Heinrich Romberg, a German neurologist, created the Romberg test to evaluate neurological function. Although it is not approved by the NHTSA, law enforcement uses it to determine intoxication. Like many field sobriety tests, it divides the suspect’s focus between a physical and a mental task.

The basis of the test is that two of the following three functions are needed to maintain balance: vision, inner ear and spacial orientation. If an individual is unable to properly balance using two of these functions, it may be an indication of a neurological problem. When administered as a field sobriety test it is evidence of intoxication.

To administer this test, the officer asks the suspect to stand with their feet together, head tilted slightly back and eyes closed. The officer asks the suspect to estimate when 30 seconds has passed, and say “stop.”

While you are balancing, the officer will look for six clues: amount and direction of swaying, eyelid/body tremors, estimate of when 30 seconds has passed, muscle tone, sounds or statements made during the test, and ability to follow directions.


Finger to Nose

balance test

The finger-to-nose test requires the suspect to close their eyes, tilt their head back slightly and touch their nose with their index finger. The suspect repeats this action three times on each hand, for a total of six attempts. The officer will instruct and demonstrate the test first. Then the suspect will perform the test as demonstrated.

While performing this test, the officer will look for a number of clues that indicate intoxication. These include: inability to follow instructions, swaying, eyelid/body tremors, speaking or making sounds during the test and failing to touch your finger to your nose. If you exhibit several of these clues, law enforcement could arrest you for driving under the influence.

DUI Arrest and Investigation

A DUI arrest begins with a law enforcement encounter, followed by a DUI investigation, and eventually an arrest.

A DUI arrest starts with an encounter with law enforcement. The following are the most common ways that law enforcement encounters a DUI driver:

  • Checkpoints
  • Traffic Stops
  • Accidents
  • Stopped Vehicle

Preliminary Investigation

Officers start by making contact with the driver of the vehicle and asking them to roll down their windows. They ask the driver for their license, registration, and proof of insurance. Although you are required to provide this documentation, you are not required to roll down your window all the way when you do so. Rolling the window down allows officers to get close enough to the driver to observe signs of alcohol intoxication. Typically officers will note an “odor of alcohol emanating from the driver” “red or watery eyes” and “slurred speech.” If officers observe these indicators, they will initiate a DUI investigation by asking you to step out of your vehicle. You may decline to exit your vehicle if an officer asks. However, if an officer lawfully orders you to exit your vehicle, failing to exit can result in additional criminal charges of delaying arrest.

DUI Investigation

Officers usually ask DUI suspects to perform field sobriety tests during the DUI investigation. Common field sobriety tests include: walk the line, stand on one leg, follow the finger (also known as Horizontal Gaze Nystagmus), and count to 30. Another common sobriety test is the preliminary alcohol screening device, which takes a breath sample. You may refuse all tests prior to your arrest, unless you are on parole or probation.

DUI Arrest

If the officer has enough indications that you are driving under the influence, they will typically ask you to stand so that they can handcuff and arrest you. Once arrested, you must provide a sample of your blood, breath, or urine for purposes of determining your blood alcohol content (BAC). If you refuse, the DMV could suspend your license for one year under Vehicle Code section 23612.

Once you are arrested, officers typically take you to jail and impound your vehicle. However, it is possible that officers will not arrest you and will issue you a notice to appear instead. Similarly, officers can release your vehicle to a sober friend or relative instead of impounding it.

Officers will also take your driver’s license and provide you with a temporary paper license good for 30 days.

Declining to cooperate

As noted above, there are certain parts of the DUI arrest that you can decline. However, failure to provide your license, registration or insurance, failure to obey a lawful order, and failure to provide a blood alcohol sample after arrest can result in additional criminal charges. If you decline to participate, make sure that is your right, and be respectful to the officer when you do so.