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Field Sobriety Tests (FST) in DUI Cases

Field sobriety tests, or FSTs, are roadside physical and mental tests that are administered by police officers to drivers who are suspected of driving a motor vehicle while under the influence of drugs or alcohol (DUI). The FSTs are administered by police officers to assist the officers form an opinion as to whether or not the driver is DUI. If a police officer reasonably suspect that the driver was DUI after administering the FSTs the officer will arrest the driver for probable cause to believe that the driver is DUI.

Note: FSTs are administered before an arrest for DUI. The driver has no legal obligation to comply with these pre-arrest tests (FSTs); however, a police officer does not have a duty to inform a driver that he or she does not have to comply with the officer's request. There is an important difference between FSTs, which a driver may refuse to perform, and chemical tests, which a driver is required to perform upon an officer's request. A chemical test is a breathlyzer tests, a blood sample, or a urine sample. See California Implied Consent Law for important distinctions between FSTs and chemical tests.

FSTs are “standardized” or “non-standardized."

Standardized FSTs Include:

Nystagmus Test: This DUI test is administered by having the driver follow an object with his or her eyes without moving his or her head. Usually the officer holds a pen or some other small object out in front of the driver about a foot from the driver's head. During the nystagmus test the officer is looking to see if the driver moves his head instead of his eyes, which might indicate intoxication. The officer is also checking to see if the driver's eyes are bouncing around, jerking, or floating within the eye socket, which might indicate intoxication.

Walk and Turn Test: This DUI test is administered by having the driver take a certain amount of steps forward and backward with the heel to toe for each step. The officer is looking for imbalance or lack of following instruction which might indicate DUI.

Rhomberg Test: This DUI test is administered by having the driver take a position of attention, close his or her eyes, tilt his or her head back, and estimate 30 seconds. The officer is looking for poort balance to indicate intoxication or poor time estimation as evidence of impairment. A "one leg stand" is a variation of the rhomberg test.

PAS Breath Test: A preliminary alcohol screening device, or PAS device, is a hand-held device that is designed to monitor breath alcohol by having the driver blow into the device for a reading of the driver’s purported BAC. Police officers use PAS devices in the field to help them assess the driver’s impairment, if any. See below for important difference between PAS devices, which are FSTs, and breathalyzers, which are chemical test.

Note: Unlike other FSTs, drivers under the age of 21 may be penalized for refusal to take a PAS device test.

Non-Standardized FSTs: Include having the driver tap fingers together, count backwards, recite ABCs backwards, etc. These non-standardized FSTs are designed to detect the driver's impairment similar to the standardized FSTs. Also, The National Highway Transportation Safety Association (NHTSA) has created a list of non-standardized cues that might assist police officers detect DUI. These tests include:

  • Driver turning with wide radius
  • Driver's drunk appearance (Eyes, Smell, Speach, etc.) 
  • Driver straddling center divider
  • Driver striking or almost striking an object
  • Weaving or swerving out of lane
  • Driver driving more than 10 miles under speed limit
  • Driver following too close to other drivers
  • Driving with no headlights
  • Driver's rapid acceleration or deceleration
  • Inappropriate stopping
  • Wrong signaling
  • Slow response to traffic signals, and more.

Implied Consent Law & FSTs v. Chemical Tests: California puts conditions on a driver’s privilege to drive in the state. One of the conditions is that a driver impliedly agrees, by virture of his or her choice to drive in California, to take a chemical test upon request by a police officer, after the driver is lawfully arrested for DUI, and after the driver was informed of pertinent portions of California's implied consent law. A chemical test means a breathalyzer test, a blood sample, or a urine sample. Unlike FSTs, which are optional tests, refusal to comply with the police officer’s request for a chemical test after a lawful arrest for DUI may result in enhanced DUI criminal penalties and license suspension.

Blood Sample Exception: Taking a driver’s blood sample after a lawful arrest for DUI requires actual driver consent, a warrant, a felony DUI charge, or an officer’s reasonable suspicion impairment by drugs.

Caution: As stated: PAS device tests are considered FSTs, not chemical tests, such as breathalyzers, which are subject to California’s implied consent law. Confusing a PAS test with a breathalyzer can lead to inadvertent refusal to take a required test governed by California’s implied consent law. PAS devices and breathalyzer can both be hand-held devices, but more commonly, the PAS device is a hand-held device used by police officers before arrest and administered at the location where the driver was pulled over or crashed and a breathalyzer machine is a larger device that is usually administered at the police station after arrest.

To learn more abbout field sobriety tests (FSTs), problems and defenses to FSTs, and other considerations in DUI law and DMV hearings, contact our DUI & DMV defense attorneys today for a free in-office consultation.


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FSTs in DUI cases

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