DWI Detection and Standardized Field Sobriety Testing (SFST) Certification — Questions and Answers

Question 1: An officer administers the HGN test but fails to document the stimulus speed used. Why is this a problem?

Stimulus speed is only documented for prescription medication cases
Moving the stimulus too fast or slow can produce false clues, so speed must be noted to validate the test (Correct answer)
Stimulus speed has no effect on HGN results and is irrelevant to documentation
Federal regulations require stimulus speed in miles per hour

Correct answer: Moving the stimulus too fast or slow can produce false clues, so speed must be noted to validate the test

The stimulus must be moved at approximately 2 seconds per pass for smooth pursuit and 4 seconds for maximum deviation, so documenting compliance with these rates validates the test results.

Question 2: Women typically achieve higher BAC levels than men after consuming the same amount of alcohol primarily because women:

Generally have a higher percentage of body fat and a lower percentage of total body water (Correct answer)
Metabolize alcohol significantly more slowly in the liver
Have blood that carries alcohol less efficiently than male blood
Have a faster resting heart rate that circulates alcohol more rapidly

Correct answer: Generally have a higher percentage of body fat and a lower percentage of total body water

Women typically have a higher body fat percentage and lower body water percentage than men of the same weight, so the same amount of alcohol is distributed in a smaller volume of water, resulting in a higher BAC.

Question 3: What role does ethics play in Walk and Turn practice?

It only matters for legal compliance
It guides professional conduct and protects stakeholders (Correct answer)
Ethics is optional in professional settings
It only applies to managers

Correct answer: It guides professional conduct and protects stakeholders

Professional ethics provide frameworks for responsible decision-making, ensuring practitioners act in the best interest of those they serve.

Question 4: Based on its effects on the central nervous system, alcohol is classified as which type of drug?

Hallucinogen
Depressant (Correct answer)
Stimulant
Narcotic

Correct answer: Depressant

Alcohol is a central nervous system depressant that slows brain function and neural activity, impairing judgment, coordination, and reaction time.

Question 5: How does documentation support quality in Observation Skills?

It only serves administrative purposes
It is only for billing
It creates records, ensures consistency, and enables improvement (Correct answer)
Documentation is unnecessary overhead

Correct answer: It creates records, ensures consistency, and enables improvement

Proper documentation creates accountability, ensures consistency, supports quality improvement, and provides legal protection.

Question 6: Alcohol absorption into the bloodstream is most rapid when alcohol is consumed:

With non-carbonated water
On an empty stomach (Correct answer)
With a large, fatty meal
In small sips over several hours

Correct answer: On an empty stomach

Without food to slow gastric emptying, alcohol passes quickly into the small intestine where the majority of rapid absorption occurs, causing BAC to rise faster.

Question 7: Carbonated mixers (such as tonic water or cola) typically have what effect on alcohol absorption?

They reduce the peak BAC achieved
They have no measurable effect on absorption rate
They significantly slow alcohol absorption
They speed up alcohol absorption into the bloodstream (Correct answer)

Correct answer: They speed up alcohol absorption into the bloodstream

Carbonation increases gastric pressure and speeds gastric emptying, causing alcohol to enter the small intestine faster and resulting in more rapid absorption.

Question 8: The primary route of alcohol elimination from the body is through:

Evaporation through the skin
Metabolism by the liver (Correct answer)
Exhalation through the lungs
Excretion through the kidneys

Correct answer: Metabolism by the liver

Approximately 90–95% of consumed alcohol is eliminated through hepatic metabolism (liver), while small amounts are excreted via breath, urine, and sweat.

Question 9: An officer is administering the One-Leg Stand and the suspect raises their arms 8 inches from their sides. How many clues does this single action represent?

Three clues because it violates multiple instructions
Two clues — raises arms and loses balance
One clue — raises arms (Correct answer)
No clues if the suspect does not fall

Correct answer: One clue — raises arms

Raising arms more than 6 inches is counted as one distinct clue regardless of the degree to which they are raised.

Question 10: Which Central Nervous System (CNS) depressants other than alcohol are known to produce HGN?

Cannabis only
Cocaine and methamphetamine
Barbiturates, benzodiazepines, and some inhalants (Correct answer)
Caffeine and nicotine

Correct answer: Barbiturates, benzodiazepines, and some inhalants

CNS depressants including barbiturates, benzodiazepines, and inhalants can produce nystagmus similar to that caused by alcohol.

Question 11: During the Walk-and-Turn, a suspect takes 17 steps on the first leg instead of the required 9. How should the officer score this?

Restart the test from the beginning
Do not score it because more steps indicate more coordination
Score 'incorrect number of steps' as one clue (Correct answer)
Score each extra step as a separate clue

Correct answer: Score 'incorrect number of steps' as one clue

Taking an incorrect number of steps (more or fewer than instructed) counts as a single scored clue on the Walk-and-Turn.

Question 12: Defense counsel asks: 'Were you wearing your body camera during the SFSTs?' If the camera malfunctioned, the officer should:

Lie and say the camera was not policy-required that night
Decline to answer the question
Claim the video exists but is unavailable
Truthfully state the camera malfunctioned and explain the documentation used instead (Correct answer)

Correct answer: Truthfully state the camera malfunctioned and explain the documentation used instead

Truthful disclosure of equipment malfunction preserves credibility and allows the officer to redirect focus to contemporaneous documentation.

Question 13: A subject who weighs 400 pounds wants to perform the OLS test. What does NHTSA guidance suggest?

Administer the test; weight is irrelevant
Double the acceptable number of clues before declaring impairment
People who are significantly overweight may have difficulty and results should be interpreted with caution (Correct answer)
Refuse to administer the test to protect the subject's health

Correct answer: People who are significantly overweight may have difficulty and results should be interpreted with caution

NHTSA acknowledges that individuals who are significantly overweight (50 or more pounds) may have genuine difficulty with OLS due to physical factors unrelated to impairment.

Question 14: What role does ethics play in Observation Skills practice?

Ethics is optional in professional settings
It only matters for legal compliance
It guides professional conduct and protects stakeholders (Correct answer)
It only applies to managers

Correct answer: It guides professional conduct and protects stakeholders

Professional ethics provide frameworks for responsible decision-making, ensuring practitioners act in the best interest of those they serve.

Question 15: What is the primary purpose of the 'divided attention' concept in SFST administration?

To measure reaction time exclusively
To test the ability to perform mental and physical tasks simultaneously, which is impaired by alcohol (Correct answer)
To demonstrate that the suspect can follow simple instructions
To confuse the suspect into making mistakes

Correct answer: To test the ability to perform mental and physical tasks simultaneously, which is impaired by alcohol

Divided attention tests reveal impairment because alcohol degrades the ability to perform simultaneous mental and physical tasks.

Question 16: A 'per se' DUI law means that a driver can be convicted because:

Chemical test results were confirmed by a second test
The driver admitted to consuming alcohol
An officer observed clear signs of impairment
The driver's BAC meets or exceeds the legal limit, regardless of observable impairment (Correct answer)

Correct answer: The driver's BAC meets or exceeds the legal limit, regardless of observable impairment

A per se law makes it illegal to drive at or above the specified BAC level automatically, without requiring separate proof of actual impairment.

Question 17: Which medical condition can produce HGN clues that may be mistaken for alcohol impairment?

Hypertension
Asthma
Inner ear disorder (labyrinthitis) (Correct answer)
Type 2 diabetes

Correct answer: Inner ear disorder (labyrinthitis)

Inner ear disorders such as labyrinthitis can cause nystagmus that mimics alcohol-induced HGN, which officers must consider.

Question 18: How should conflicting observations — such as a subject passing HGN but failing the WAT — be handled in documentation?

Mark the conflicting test results as invalid and request a blood draw only
Report only the test that shows the most impairment and omit the other
Report both tests but assign equal weight to each clue regardless of SFST type
Document all test results accurately and let the totality of observations guide the arrest decision (Correct answer)

Correct answer: Document all test results accurately and let the totality of observations guide the arrest decision

All SFST results must be accurately documented regardless of consistency; the arrest decision is based on the totality of observations, not a single test outcome.

Question 19: Which of the following is a consequence of an officer failing to document that a subject was instructed to keep arms at their sides during the One-Leg Stand?

Defense may argue improper administration, potentially invalidating the OLS clues (Correct answer)
The test score doubles under NHTSA rules
The officer must re-administer the test at booking
The charge must be reduced from DUI to a traffic infraction

Correct answer: Defense may argue improper administration, potentially invalidating the OLS clues

Failure to document that standardized instructions were given allows defense to challenge whether the test was administered correctly, undermining the reliability of observed clues.

Question 20: A subject performs the HGN test but keeps closing one eye. How should this be documented?

Mark both eyes as zero clues since the test was incomplete
Terminate the report and proceed directly to a blood draw
Record the behavior as an observation affecting test validity and note clues observed in the open eye (Correct answer)
Count the closed eye as automatically showing all 3 clue types

Correct answer: Record the behavior as an observation affecting test validity and note clues observed in the open eye

The subject's non-cooperative behavior must be documented as an observation, and any clues observed in the eye that remained open should still be recorded.

Question 21: What is the evidentiary purpose of an officer referencing NHTSA training materials during court testimony?

To establish that the tests were administered according to validated, standardized procedures (Correct answer)
To impress the jury with technical jargon
To introduce evidence that was not part of the original report
To show the officer personally invented the tests

Correct answer: To establish that the tests were administered according to validated, standardized procedures

Referencing NHTSA standards confirms the officer followed validated protocols, supporting admissibility and weight of SFST evidence.

Question 22: During cross-examination, defense asks whether divided-attention tasks differ from field sobriety tests. The officer should explain that:

SFSTs are specifically designed as divided-attention tests that reveal impairment by requiring simultaneous mental and physical tasks (Correct answer)
SFSTs test physical balance only, not cognitive function
SFSTs have nothing to do with divided attention
Divided attention is only relevant to driving performance

Correct answer: SFSTs are specifically designed as divided-attention tests that reveal impairment by requiring simultaneous mental and physical tasks

The divided-attention design of SFSTs replicates the cognitive demands of driving, making performance on them relevant to driving impairment.

Question 23: Under most U.S. zero-tolerance laws, drivers under the age of 21 may be charged with DUI at a BAC of:

0.10% or higher
0.04% or higher
0.02% or higher (Correct answer)
0.08% or higher

Correct answer: 0.02% or higher

Most states have adopted zero-tolerance laws setting the BAC limit for drivers under 21 at 0.02% (effectively zero), reflecting that any alcohol consumption by minors is illegal.

Question 24: A suspect tells the officer they have an inner ear condition before SFSTs begin. The officer should:

Skip only the HGN test and proceed with balance tests
Immediately request a blood draw without administering any SFSTs
Disregard the claim and administer all tests normally
Document the condition and consider its potential effect on balance test results (Correct answer)

Correct answer: Document the condition and consider its potential effect on balance test results

Known medical conditions affecting balance or vision must be documented and considered when interpreting SFST results.

Question 25: What does BAC stand for in the context of DUI enforcement?

Breath Alcohol Calculation
Blood Alcohol Concentration (Correct answer)
Body Alcohol Content
Blood Alcohol Component

Correct answer: Blood Alcohol Concentration

BAC stands for Blood Alcohol Concentration, which measures the amount of alcohol in a person's bloodstream expressed as a percentage.

Question 26: What role does ethics play in Legal Standards practice?

It only applies to managers
Ethics is optional in professional settings
It only matters for legal compliance
It guides professional conduct and protects stakeholders (Correct answer)

Correct answer: It guides professional conduct and protects stakeholders

Professional ethics provide frameworks for responsible decision-making, ensuring practitioners act in the best interest of those they serve.

Question 27: In most U.S. states, the per se BAC limit for non-commercial adult drivers is:

0.08% (Correct answer)
0.05%
0.06%
0.10%

Correct answer: 0.08%

The federally encouraged and most widely adopted per se BAC limit for adult non-commercial drivers in the U.S. is 0.08%.

Question 28: Which of the following correctly describes the recommended speed for moving the stimulus during the Lack of Smooth Pursuit check?

As fast as possible to catch jerking motion
Approximately two seconds from center to the edge of each eye
Four seconds from center to the edge of each eye (Correct answer)
One full sweep (left to right) in one second

Correct answer: Four seconds from center to the edge of each eye

NHTSA instructs the officer to take approximately four seconds to move the stimulus from center to the maximum deviation of each eye during the smooth pursuit check.

Question 29: In the context of SFST professional development, what does 'field validation' of skills refer to?

Validating test results against a breathalyzer in the field
Demonstrating proper SFST administration during actual or supervised operational DUI stops (Correct answer)
Completing an online exam at a field station
Having a supervisor sign a checklist without observation

Correct answer: Demonstrating proper SFST administration during actual or supervised operational DUI stops

Field validation refers to demonstrating correct SFST administration under real or realistically supervised conditions, not just in a classroom setting.

Question 30: Approximately how long does it take the average adult liver to metabolize one standard drink?

One hour (Correct answer)
Two hours
45 minutes
30 minutes

Correct answer: One hour

On average, the human liver metabolizes alcohol at a rate of approximately one standard drink per hour, though this varies by individual.

Question 31: Vertical Gaze Nystagmus (VGN) is typically associated with BAC levels at or above:

0.08%
0.15% (Correct answer)
0.06%
0.04%

Correct answer: 0.15%

Vertical Gaze Nystagmus generally indicates a very high BAC (typically 0.15% or above) or the influence of certain drugs, and is not present at moderate BAC levels.

Question 32: Under federal regulations, the per se BAC limit for operators of commercial motor vehicles (CMV) is:

0.02%
0.04% (Correct answer)
0.08%
0.06%

Correct answer: 0.04%

Federal law (49 CFR Part 382) sets the BAC limit for CMV operators at 0.04%, half the standard adult limit, due to the increased public safety risk posed by large commercial vehicles.

Question 33: Which case recognized that a warrantless blood draw may be justified by exigent circumstances in a DUI investigation?

Schmerber v. California (Correct answer)
Illinois v. Wardlow
Terry v. Ohio
Mapp v. Ohio

Correct answer: Schmerber v. California

Schmerber v. California held that the natural dissipation of blood alcohol can constitute exigent circumstances justifying a warrantless blood draw.

Question 34: Alcohol-induced nystagmus occurs primarily because alcohol impairs the function of which part of the brain?

Hypothalamus
Temporal lobe
Cerebral cortex
Cerebellum (Correct answer)

Correct answer: Cerebellum

Alcohol disrupts the cerebellum and brainstem, which control smooth tracking eye movements, causing the jerking motion observed as horizontal gaze nystagmus.

Question 35: When documenting the subject's eye condition for HGN, why should the officer record whether the subject is wearing contact lenses?

Contacts affect BAC readings on preliminary breath tests
Contacts legally exempt the subject from the HGN evaluation
Contact lenses can cause false positives for lack of smooth pursuit in some individuals (Correct answer)
Contact lenses require the officer to skip the HGN test entirely

Correct answer: Contact lenses can cause false positives for lack of smooth pursuit in some individuals

Hard contact lenses in particular can create optical artifacts that may mimic nystagmus, so noting their presence protects the validity of HGN documentation.

Question 36: A prosecutor requests that an SFST officer inflate clue counts in the written report. The officer should:

Consult a defense attorney first
Comply if instructed by a superior
Refuse and report the request through proper channels (Correct answer)
Amend the report to satisfy the prosecutor

Correct answer: Refuse and report the request through proper channels

Officers must refuse requests to falsify reports and should report such misconduct through appropriate channels.

Question 37: An officer is asked if they have ever arrested someone for DUI who later proved sober. The officer should:

Acknowledge that errors can occur and explain the safeguards in place to minimize them (Correct answer)
Refuse to answer on grounds of self-incrimination
Change the subject
Deny any such occurrence

Correct answer: Acknowledge that errors can occur and explain the safeguards in place to minimize them

Acknowledging fallibility while explaining procedural safeguards demonstrates integrity and is more persuasive to juries than claiming infallibility.

Question 38: During the Walk-and-Turn, the subject takes 9 steps heel-to-toe, turns, and takes 9 steps back. How many steps is the subject supposed to take in each direction?

8 steps
10 steps
9 steps (Correct answer)
12 steps

Correct answer: 9 steps

The standardized WAT requires 9 heel-to-toe steps forward and 9 heel-to-toe steps back along the line.

Question 39: An officer who arrests a sober driver based solely on a medical condition that mimics intoxication may face civil liability under:

The Americans with Disabilities Act only
Title VII of the Civil Rights Act
The NHTSA certification agreement
42 U.S.C. § 1983 for civil rights violations (Correct answer)

Correct answer: 42 U.S.C. § 1983 for civil rights violations

Section 1983 allows individuals to sue state actors for violations of constitutional rights, including unlawful arrest.

Question 40: What are standard precautions in healthcare?

Only wearing gloves for known infections
Hand washing after patient contact only
Treating all blood and body fluids as potentially infectious (Correct answer)
Using masks during surgery only

Correct answer: Treating all blood and body fluids as potentially infectious

Standard precautions assume all blood and body fluids are potentially infectious, requiring consistent use of barriers (gloves, gowns, masks) and hand hygiene for all patient interactions.

Question 41: In a DUI case, hearsay testimony about a bystander's report that the driver 'was swerving' is generally:

Admissible as an excited utterance if made shortly after witnessing the event (Correct answer)
Admissible only if the bystander is also arrested
Admissible as a business record
Always admissible to establish probable cause

Correct answer: Admissible as an excited utterance if made shortly after witnessing the event

An excited utterance — a spontaneous statement made under stress of excitement from a startling event — is a recognized hearsay exception.

Question 42: During the One-Leg Stand, which clue is recorded when the subject puts their raised foot down before the count is complete?

Puts foot down (Correct answer)
Uses arms for balance
Hopping
Swaying

Correct answer: Puts foot down

Puts foot down is the specific NHTSA clue recorded when the subject lowers their raised foot before being instructed to stop.

Question 43: Which of the following is a valid reason to stop a One-Leg Stand before 30 seconds have elapsed?

The subject is at risk of falling and may be injured (Correct answer)
The subject shows 2 or more clues within the first 10 seconds
The officer believes the subject has clearly failed
The subject requests to stop

Correct answer: The subject is at risk of falling and may be injured

Officer safety and subject welfare require stopping the test if the subject is at genuine risk of falling and injuring themselves.

Question 44: According to NHTSA research, measurable impairment of driving-related skills can begin at a BAC as low as:

0.10%
0.02% (Correct answer)
0.05%
0.08%

Correct answer: 0.02%

NHTSA research indicates that some driving-related skills, particularly divided attention tasks, begin to be measurably impaired at BAC levels as low as 0.02%.

Question 45: An officer who coaches a witness to match the officer's SFST report testimony commits:

Inadvertent discovery
Proper law enforcement coordination
A violation of chain of custody only
Witness tampering or obstruction of justice (Correct answer)

Correct answer: Witness tampering or obstruction of justice

Coaching witness testimony to align with an officer's version of events constitutes witness tampering and obstruction of justice.

Question 46: When should you change an answer on a test?

Only when you have a clear reason the new answer is better (Correct answer)
Never change answers
Always change your first answer
Change every answer you doubt

Correct answer: Only when you have a clear reason the new answer is better

Research shows changing answers is beneficial only when you have a specific reason, such as recalling new information or catching a misread question.

Question 47: Alcohol is distributed throughout the body primarily via body water because:

Alcohol is water-soluble and distributes through total body water (Correct answer)
Alcohol is stored in adipose (fat) tissue for slow release
Alcohol is too large a molecule to enter fatty tissue
Alcohol binds to hemoglobin in red blood cells

Correct answer: Alcohol is water-soluble and distributes through total body water

Alcohol is highly water-soluble and distributes evenly throughout the body's total water content, which is why body composition (water vs. fat percentage) affects BAC.

Question 48: Which detail about the HGN stimulus object must be documented to ensure test validity?

The subject's visual acuity prescription if available
That the stimulus was held 12–15 inches from the subject's nose at eye level (Correct answer)
The officer's dominant hand used to hold the stimulus
The color and brand of the stimulus object used

Correct answer: That the stimulus was held 12–15 inches from the subject's nose at eye level

NHTSA standards require the stimulus to be held 12–15 inches from the nose at eye level; documenting this confirms the test was administered within the validated parameters.

Question 49: What does informed consent require?

Explaining the procedure, risks, benefits, and alternatives to the patient (Correct answer)
Getting any signature on a form
Verbal agreement only
Family approval only

Correct answer: Explaining the procedure, risks, benefits, and alternatives to the patient

Informed consent requires that patients understand the proposed procedure, its risks and benefits, alternatives, and have the opportunity to ask questions before agreeing.

Question 50: Which professional development activity specifically targets SFST instructors rather than general practitioners?

Instructor Development Courses (IDC) or Instructor Certification Programs (Correct answer)
Annual firearms qualification
Basic HGN training
Preliminary Breath Test (PBT) certification

Correct answer: Instructor Development Courses (IDC) or Instructor Certification Programs

Instructor Development Courses train practitioners how to teach SFST effectively and are a prerequisite for becoming a certified SFST instructor.

DWI Detection and Standardized Field Sobriety Testing (SFST) Certification

The NHTSA/IACP SFST certification exam tests law enforcement officers on DWI detection procedures, standardized field sobriety test administration (HGN, Walk-and-Turn, One-Leg-Stand), alcohol physiology, documentation, and courtroom testimony. A passing score of 80% is required for certification.

Questions

60 min

Time Limit

80%

To Pass

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