If you get stopped for DUI in Nevada, the police will typically ask you to perform a series of field sobriety tests (FSTs). The three standardized FSTs are:
You are under no legal obligation to take these tests, and most defense attorneys would advise that you should politely decline.
The federal agency NHTSA (National Highway Traffic Safety Administration) developed these FSTs and provide law enforcement agency officers with detailed instructions on how to administer and score them. Though in practice, FSTs are not always reliable indicators of alcohol impairment.
Poor FST performance can result from factors unrelated to drug or alcohol use, such as:
- improper administration of the tests by police,
- unfavorable settings and surroundings,
- certain medications, and
- illness or injury
A skilled Nevada criminal defense attorney may be able to show that
- a failing FST score does not mean that you were driving under the influence of alcohol or drugs, and
- any DUI charges should be dropped.
In this article, our Las Vegas DUI attorneys discuss:
- 1. Am I required to take field sobriety tests?
- 2. Are FSTs scientifically valid?
- 3. How can my attorney attack FSTs in court?
- 4. What are the standardized field sobriety tests in Nevada?
- 5. What happens before the FSTs?
- 6. What happens after the FSTs?
- 7. How about non-standardized field sobriety tests?
1. Am I required to take field sobriety tests?
No. FSTs are not mandatory in Nevada even though the police may claim they are.1
Therefore you can politely decline to take the FSTs. That way, the state has less evidence to prove its case against you.
However, declining the FSTs likely ensures that the police officer will arrest you. Police construe FST refusals as a consciousness of guilt.
Note that officers should not administer FSTs on DUI suspects who are clearly too incapacitated or injured to comply.2 Officers also should not administer FSTs if there is no safe and appropriate space to perform them.3
2. Are FSTs scientifically valid?
No. One out of four people who fail FSTs is not under the influence of drugs or alcohol. Therefore, the tests’ accuracy rates are very low:4
|Standardized Field Sobriety Test||Reliability Rate for Determining DUI|
|Horizontal Gaze Nystagmus||77%|
|Walk and Turn||68%|
Through NHTSA, the US Department of Transportation outlines specific instructions about how to administer the tests and what “clues” police should look for to detect intoxication. The D.A. then uses failing FST results in court to try to prove that the defendant:
- was impaired by alcohol or drugs, or
- has an illegal blood alcohol content (BAC) of .08% or higher.
However, many non-DUI circumstances can cause false positives:
- Poor testing conditions
- road and sidewalk surfaces that are uneven, soft, wet, or slippery
- windy or rainy weather
- unsuitable footwear, or lack of footwear
- poor lighting for the officer to observe the suspect
- disruptive visual and audial distractions such as traffic, bright lights, sirens, honking, and spectators
- Adverse physical or medical conditions
- inner ear problems
- mental disabilities
- prescribed medication that may hinder coordination or cause nystagmus
- physical limitations such as old age, injury, illness, or obesity
- tight or uncomfortable clothing
- back or leg problems
- Officer misconduct
- incorrect, inaudible, or misleading instructions and directions
- distracting movements or statements
- bias against the suspect
In sum, several factors can cause a sober person to exhibit false clues during FSTs in Nevada.
3. How can my attorney attack FSTs in court?
Having represented hundreds of clients accused of drunk driving in Nevada, we rely on these four defenses to invalidate FST results:
- FSTs are unreliable
- The setting was improper
- You had a physical condition that caused a false positive
- The police made mistakes
3.1. FSTs are unreliable
FSTs have a significant fail rate: 25% of people who fail FSTs are in fact sober. Depending on the test, FSTs are only 65% to 77% reliable.
Furthermore, FSTs are their least unreliable when a suspect is:
- perfectly healthy,
- physically fit,
- wide awake,
- mentally uncompromised,
- emotionally calm, and
- wearing athletic clothing.
Most DUI suspects fall short of these standards. Any reasonable person would be extremely nervous to perform FSTs and would find the instructions confusing.
A defense attorney would argue that these statistics and common sense should cast significant doubt on your FST results.
3.2. The setting was improper
FSTs must take place in an environment that maximizes your chances of success. FSTs can render false positives by a
- poor walking surface,
- inclement weather,
- disruptive noises, and
- other variables.
A DUI defense attorney should conduct a thorough investigation to find video surveillance footage and eyewitness testimony of your FSTs. Such evidence could show that the surrounding circumstances set you up to fail.
3.3. You had a physical condition that caused a false positive
Medical and psychological conditions can prevent sober people from passing FST tests. For example:
- a head injury may cause nystagmus5
- a bad back could make it impossible to perform the one-legged stand
- high anxiety could make it impossible to remember all the instructions for the walk-and-turn
A defense attorney could use your medical records to help show that you were physically incapable of passing the FSTs.
3.4. The police made mistakes
Scoring FSTs is extremely subjective.
Maybe the officer thought they saw you exhibit a “clue” when in fact it was too dark out to see clearly. Or perhaps the police forgot to mention that arms cannot be used for balance during the walk-and-turn and one-legged stand, and you used your arms without realizing it was against the rules.
The police officer’s body cam or dash cam footage could prove invaluable in showing that the police officer was at fault.
In addition, defense attorneys should aggressively cross-examine the officers during the DMV hearing, which is where you contest the DMV‘s revocation of your driver’s license. Since the DMV case is separate from the criminal case, the DMV hearing is a good opportunity to test the officer’s credulity and uncover weak spots in the state’s evidence that can then be used in your favor in the criminal case.
When an attorney uncovers problems with the FSTs, it gives you a bargaining chip when negotiating with the prosecutor: Perhaps the D.A. would be willing to reduce the DUI charge to reckless driving or even a full dismissal. Or if the case goes to trial, such evidence may make it impossible for the prosecutor to prove guilt beyond a reasonable doubt.
4. What are the standardized field sobriety tests in Nevada?
Standardized Field Sobriety Tests (FSTs) are physical exercises that police ask DUI suspects to perform to determine whether they are under the influence of drugs or alcohol.
Nevada’s standardized FSTs consist of three separates tests:
- Horizontal Gaze Nystagmus,
- Walk-and-Turn, and
- One-Legged Stand6
4.1. Horizontal Gaze Nystagmus (HGN)
Also called the pen test, the Horizontal Gaze Nystagmus test is an eye test where you are instructed to keep your eyes fixed on the officer’s penlight (or another object) as the officer moves it from side to side. In the meantime, the officer is observing your pupils for an involuntary jerking — called “nystagmus” — which can indicate impairment.
Specifically, the police officer is checking for three “clues” of intoxication in each eye:
- Lack of smooth pursuit. This is where the pupil spontaneously jerks while following the police officer’s penlight. Theoretically, a sober person’s eyes would move smoothly.
- Distinct nystagmus at maximum deviation. For four seconds, the officer holds the penlight very far to the side so the suspect’s pupils are at “maximum deviation.” If the pupils bounce (“jerking of the eyes”), it may be a sign of a high BAC level.
- Onset prior to 45 degrees. As the officer moves the penlight back and forth, the officer is studying whether the suspect’s pupils jerk prior to the penlight being at a 45-degree angle away from the suspect’s face. If the pupils do jerk, it could be a sign of intoxication.
During the HGN test, the officer is tallying how many “clues” each eye is exhibiting. The maximum number of clues a suspect can show is six (which is three for each eye). Exhibiting four or more clues is a failing score.7
4.2. Walk-and-Turn (WAT)
The Walk and Turn test is a physical agility and coordination test. You are instructed to take nine (9) steps heel-to-toe back and forth in a straight line.
In addition, you have to keep one foot on the ground as you pivot around during the halfway point. Finally, you have to count the numbers aloud.
In the meantime, the police officer is looking for eight “clues” of intoxication:
- Losing balance while the police officer is giving instructions.
- Starting to walk before the police officer finishes giving the instructions.
- Pausing during the walk. (Walking slowly is okay as long as there is no stopping.)
- Not walking heel-to-toe.
- Stepping out of line.
- Using arms to balance.
- Losing balance while doing the turn.
- Taking an incorrect number of steps.
Showing two or more clues during the WAT test is a considered failing score.8
4.3. One-legged stand (OLS)
For the One Leg Stand test, Nevada police have you stand in place on one leg while keeping the other leg extended forward about six inches off the ground. Simultaneously, you have to count aloud to 30 by reciting “one one-thousand, two one-thousand, three one-thousand…” etc.
Like the WAT, the OLS is considered a divided attention test because your mind has to multitask between physical exercise and counting aloud.
Meanwhile, the police officer is looking out for the following four “clues” of intoxication:
- Putting the raised foot down.
- Using arms for balance.
Exhibiting two or more clues in the OLS test is deemed a failing score. Incorrectly counting the numbers does not negatively impact the score, though the officer will take it as further probable cause you are impaired.9
5. What happens before the FSTs?
After a law enforcement officer pulls you over for a traffic stop on suspicion of DUI, the officer will first ask some cognition-testing questions such as requesting that you take out your driver’s license and registration.
Meanwhile, the officer will closely observe your demeanor for signs of intoxication, including:
- the odor of alcohol or marijuana
- glassy, watery, or red/bloodshot eyes
- flushed face
- lack of coordination
- slurred speech or slow responses
- open containers or drug paraphernalia in the vehicle
If you are manifesting these signs of intoxication, the police officer will then ask you to exit the vehicle and perform the FSTs.
6. What happens after the FSTs?
If you do not pass the FSTs, the police officer will then ask you to submit to a preliminary breath test (PBT) to see if the results are .08% or higher (which is above the legal limit). Then depending on the results and surrounding circumstances, the officers may decide they have probable cause for a DUI arrest.10
Note that whether you get arrested for DUI is up to the police officer’s discretion. In some cases, the police may decide there is probable cause to believe you are under the influence even if you pass the FSTs and PBT.
6.1. Evidentiary tests
Following a DUI arrest, Nevada law requires you to submit to an evidentiary DUI breath test or a DUI blood test. (If the officer suspects DUI of controlled substances, you have to take the blood test since breathalyzer tests do not register narcotics levels.)11
If you refuse to submit to a chemical test of breath or blood, the police can physically constrain you to get a blood sample by force. The police just need to get a warrant first so that the blood test results will be admissible in court.12
7. How about non-standardized field sobriety tests?
Some “non-standardized” field sobriety tests exist, but Nevada police rarely use them. This is because no national, reliable studies exist that demonstrate any correlation between the test results and the driver’s impairment. These non-standardized FSTs are:
|Rhomberg stationary balance test||You stand upright with feet together while leaning your head back and holding out your arms to the side.|
|Finger-to-nose test||You close your eyes, reach out your dominant arm, and then try to touch your nose with your index finger. This is a routine test in neurology exams.|
|Finger count test||The officer raises their hand, and you count the number of fingers the officer is displaying. This test is meant to detect whether your vision is blurry.|
|Hand pat test||You extend one arm in front of you palm up. Then you place your other hand on top of the first palm down. Then the top hand pats the bottom hand while flipping it 180 degrees between pats. Meanwhile, you count aloud, “one, two, one, two…” with every pat.|
|Vertical gaze nystagmus||The officer holds up a penlight about a foot in front of your nose and moves it up and down. Then you keep your head still while following the stimulus with your eyes.|
|ABC test||The officer asks you to recite a portion of the alphabet.|
|Numbers backward test||The officer asks you to count backward from one number to another.13|
If a Nevada police officer does administer these non-standardized FSTs, your DUI defense attorney can seek to have them excluded from evidence for lack of scientific basis.
NHTSA considers the HGN, WAT and OLS tests to be “standardized” field sobriety tests because studies show some correlation between the test results and the driver’s impairment. Though as discussed above, even the standardized FSTs are unreliable.
For additional help…
If you have been accused of driving while impaired as a misdemeanor or felony DUI, call our Las Vegas criminal defense attorneys for a consultation. We will investigate every aspect of your DUI case including the standardized field sobriety tests (SFSTs) to try to get the charges reduced or dismissed. If necessary, our Las Vegas DUI lawyers can take the matter all the way to trial in pursuit of a not guilty verdict.
Our Nevada DUI lawyers represent clients throughout the state, including Las Vegas, Henderson, Clark County, Washoe County, Reno, Carson City, Laughlin, Mesquite, Moapa, Elko, Pahrump, and Tonopah. Every day, criminal defense lawyers appear in the Regional Justice Center at 200 Lewis Avenue, Las Vegas, NV 89101.
Arrested in California? See our article on field sobriety tests in California DUI law.
Arrested in Colorado? See our article on field sobriety tests in Colorado DUI law.
- See, for example, Department of Motor Vehicles & Pub. Safety v. Evans, (1998) 952 P.2d 958, 114 Nev. 41 (the defendant refused to take two of the three FSTs).
- See, for example, Department of Motor Vehicles v. Torres, (1989) 779 P.2d 959, 105 Nev. 558 (the defendant was asleep behind the wheel).
- See, for example, Department of Motor Vehicles & Pub. Safety v. Becksted, (1991) 813 P.2d 995, 107 Nev. 456 (“No field sobriety test was administered for safety reasons.”)
- NHTSA Student Manual at VIII/3-14; see also Stuster & Burns, Validation of the Standardized Field Sobriety Test Battery at BACs Below .10 percent, U.S. Dept. of Transportation Rep. No. Dot-HS-808-839 (1998), at 33; Burns & Moskowitz, Psychophysical Tests for DWI Arrest, U.S. Dept. of Transportation Rep. No. DOT-HS-802-424 (1977); Anderson, Schweitz & Snyder, Field Evaluation of Behavioral Test Battery for DWI, U.S. Dept. of Transportation Rep. No. DOT-HS-806-475 (1983). The Southern California Research Institute (or “SCRI”) was commissioned by NHTSA to develop the FSTs in 1975, with a subsequent study done in 1981. Jack Stuster, Jack, and Marcelline Burns, Validation of the Standardized Field Sobriety Test Battery at BACs below 0.10 Percent, NHTSA (August 1, 1998).
- See, for example, Department of Motor Vehicles & Pub. Safety v. McLeod, (1990) 801 P.2d 1390, 106 Nev. 852 (field sobriety tests were invalidated because of defendant’s head injury).
- U.S. Department of Transportation “DWI Detection and Standardized Field Sobriety Testing” NHTSA Student Manual (October 2015).
- Wilkinson, Kime (1974) (oral dose of alcohol-impaired eye movement of all subjects); Lehti, The Effect of Blood Alcohol Concentration on the Onset of Nystagmus, 136 BLUTALKOHOL 414 (West Germany 1976); NHTSA Student Manual (2006) at VIII/4. See, for example, Wright v. State DMV (2005) ; Rodriguez v. State (Court of Appeals, 2015) 131 Nev. 1339; Gordon v. State (2005) ; Holmes v. State (2021) 498 P.3d 772; Cote v. State (2019) .
- NHTSA Student Manual at VIII/4.
- Id., at VIII/13, VIII/14, and VII/6.
- NRS 484C.150. Note that DUI suspects give “implied consent” to take a PBT. Suspects who refuse will have their license confiscated immediately and face a one (1) year-long license revocation. See also Weaver v. State (2005) ; Johnson v. State (1995) .
- NRS 484C.160. Note that DUI suspects give “implied consent” to take an evidentiary breath or blood test; Missouri v. McNeely, 569 U.S. 141 133 S.Ct. 1552 (2013).
- NHTSA Student Manual at VIII/7.