Nevada Field Sobriety Tests (FSTs): Laws, Accuracy, & Defense Strategies

If you are pulled over on suspicion of DUI in Nevada, the law enforcement officer will likely ask you to exit your vehicle and perform a series of physical and mental exercises known as field sobriety tests (FSTs).

While officers present FSTs as mandatory scientific tools, they are highly subjective and often administered incorrectly. Our Las Vegas DUI attorneys have a long track record of exposing the flaws in these tests to protect your driving record and your freedom.

Are Field Sobriety Tests Mandatory in Nevada?

No. Contrary to what an officer may imply at the scene, you have a right to refuse FSTs in Nevada.

• No Legal Penalty for Refusal: Unlike the preliminary breath test (PBT) or the evidentiary blood or breath test, refusing an FST does not result in an automatic license revocation under Nevada’s “implied consent” laws.¹
• The Risk of Refusal: While you cannot be penalized for refusing, the officer will almost certainly use your refusal as “consciousness of guilt” to establish probable cause for an arrest.
• The Strategy: In most cases, it is advantageous for your case to politely decline FSTs. This prevents the prosecution from gaining subjective “evidence” of your impairment (such as swaying or failing to follow instructions).

The Three “Standardized” Tests (SFSTs)

The National Highway Traffic Safety Administration (NHTSA) has validated only three tests as “standardized.” If an officer deviates from the specific wording or conditions in the NHTSA SFST Student Manual, the results may be inadmissible in Nevada courts.²

1. Horizontal Gaze Nystagmus (HGN)

Commonly called the “penlight test,” the HGN is where the officer looks for an involuntary jerking of the eye (nystagmus).

• The Clues: The officer looks for three clues in each eye (six total): (1) Lack of smooth pursuit, (2) Distinct nystagmus at maximum deviation, and (3) Onset of nystagmus prior to 45 degrees. Exhibiting four or more clues is failing.
• Accuracy: NHTSA claims 77% reliability, which is rather low.
• Defense: Nystagmus can be caused by over 40 medical conditions, including inner ear issues, caffeine, or certain prescription medications.

2. Walk-and-Turn (WAT)

The WAT is a “divided attention” test requiring you to multitask mentally and physically.

• The Clues: The officer looks for eight clues, such as starting before instructions are finished, losing balance during the turn, or taking the wrong number of steps. Exhibiting two or more clues is failing.
• Accuracy: NHTSA claims 68% reliability, which is very low.
• Defense: This test is highly susceptible to “environmental” failures, such as passing traffic, uneven pavement, or wind.

3. One-Leg Stand (OLS)

OLS is the test where you must stand on one leg and count aloud for 30 seconds.

• The Clues: The officer looks for four clues: (1) Sways while balancing, (2) Uses arms for balance, (3) Hopping, and (4) Puts foot down. Exhibiting two or more clues is failing.
• Accuracy: NHTSA claims 65% reliability, which makes the OLS the least reliable of all the SFSTs.
• Defense: Physical factors like being 50+ lbs overweight, back injuries, or being over age 65 can invalidate this test according to NHTSA’s own guidelines.³

Why FSTs Lead to False Positives

One out of four people who “fail” an FST is actually sober.⁴ In Nevada, we challenge results based on:

• Environmental factors, such as poor lighting, sirens/flashing lights, sloped or wet asphalt.
• Physical factors, such as inner ear infections, obesity, leg/back injuries, or fatigue.
• Officer errors, such as improper instructions, “clue” counting bias, or failing to ask about medical issues first.⁵
• Your attire, such as high heels (two-plus inches), tight clothing, or restrictive boots.

The  “50/65/2” rule refers to how the WAT and OLS can be challenged if you are more than 50 lbs, older than 65 years, or are wearing heels higher than two heels without being offered the chance to remove them.

Non-Standardized Tests

Officers sometimes use “non-standardized” tests, which have zero scientific validation for determining BAC levels. These include:

• Rhomberg Stationary Balance: Standing with head back and eyes closed.
• Finger-to-Nose: Touching your nose with your eyes closed.
• Finger Count: Touching your thumb to each finger while counting.

In Nevada, we frequently file motions in limine to exclude these from trial because they lack the “scientific reliability” required under law. While these are often used in DUID (Drug Impairment) cases, they fail the “General Acceptance” test in the scientific community.⁶

How We Fight Your FST Results

Our Las Vegas DUI attorneys utilize a multi-pronged defense strategy:

1. Motion to Suppress: If the officer lacked reasonable suspicion to stop you or probable cause to arrest you, we move to have all FST evidence thrown out.
2. Cross-Examination of the Manual: We compare the officer’s body-cam footage against the NHTSA Student Manual. If they missed a single instructional step, the “standardization” is broken.⁷
3. Medical Experts: We use medical experts to testify that your “nystagmus” or “lack of balance” was due to a pre-existing condition, not alcohol.

The HGN test is only 77% reliable.

Frequently Asked Questions

Can I record the FSTs on my phone?

Yes, you have a First Amendment right to record police interactions in public. However, do not interfere with their investigation, or you may be charged with Resisting an Officer.

What if I passed the FSTs but was still arrested?

Officers have broad discretion. If they claim to smell alcohol or see bloodshot eyes, they may arrest you despite “passing” scores. We use the “pass” to argue that the arrest was unlawful.

Does a bad back help my case?

Yes. If you have a documented history of back, knee, or hip issues, the Walk-and-Turn and One-Leg Stand tests are fundamentally unfair and medically invalid.

Legal References