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

Question 1: A person with a leg injury causing an uneven gait is asked to perform the OLS. What is the best course of action?

Administer the test and disregard the injury
Allow the subject to choose which leg to raise
Use only the first 15 seconds of the test
Do not use OLS; rely on other validated tests or observations (Correct answer)

Correct answer: Do not use OLS; rely on other validated tests or observations

Physical impairments that affect balance, such as leg injuries, can invalidate OLS results; officers should note the condition and use alternative assessments.

Question 2: A subject completes the Walk-and-Turn but uses 10 steps instead of the required 9 on the return. How should the officer document this?

Record it as an incorrect number of steps, which is one of the 8 standardized WAT clues (Correct answer)
Do not note it since the wrong number of steps is not an official WAT clue
Count it only if the subject also missed the heel-to-toe requirement
Mark the entire test invalid and start over

Correct answer: Record it as an incorrect number of steps, which is one of the 8 standardized WAT clues

Taking an incorrect number of steps is one of the 8 standardized Walk-and-Turn clues and must be recorded as observed.

Question 3: An officer testifies they detected a strong odor of alcohol from the driver. Defense counters that odor alone proves nothing. The officer's best supplemental testimony is:

Agree that odor is irrelevant
Explain that odor was one of multiple indicators observed, including slurred speech and bloodshot eyes (Correct answer)
Withdraw mention of odor from testimony
State that odor always means impairment

Correct answer: Explain that odor was one of multiple indicators observed, including slurred speech and bloodshot eyes

Odor is a component of the totality of observations; presenting it alongside other indicators reinforces a holistic impairment picture.

Question 4: Which cognitive skill is typically the first to be negatively affected by alcohol consumption?

Vision acuity
Divided attention (Correct answer)
Long-term memory recall
Gross motor coordination

Correct answer: Divided attention

Divided attention — the ability to perform two or more tasks simultaneously — is among the first cognitive skills impaired by alcohol, making it a key focus of SFSTs.

Question 5: 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 too large a molecule to enter fatty tissue
Alcohol is stored in adipose (fat) tissue for slow release
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 6: Which of the following factors does NOT affect an individual's BAC level?

Rate of consumption
Food in the stomach
Body weight
Eye color (Correct answer)

Correct answer: Eye color

Eye color has no physiological relationship to how alcohol is absorbed or metabolized; BAC is influenced by weight, consumption rate, food, and gender.

Question 7: Why is reading the question carefully important?

To memorize the question
To avoid misinterpreting what is being asked (Correct answer)
It doesn't matter
To waste time

Correct answer: To avoid misinterpreting what is being asked

Many wrong answers result from misreading questions. Key words like 'NOT,' 'EXCEPT,' 'BEST,' or 'MOST' can completely change what's being asked.

Question 8: When an SFST instructor teaches a practitioner course, what document must be submitted to the state certifying authority upon completion?

Course roster and completion records (Correct answer)
A chain-of-custody form
A grand jury subpoena
A sworn affidavit of accuracy

Correct answer: Course roster and completion records

Instructors must submit a course roster and completion records to the state certifying authority to document who passed the training.

Question 9: Carbonated mixers (such as tonic water or cola) typically have what effect on alcohol absorption?

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

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

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

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 11: During the instruction phase of the Walk-and-Turn, the officer tells the suspect 'Do not start until I tell you to.' The suspect begins walking during instructions. The officer should:

Score a clue for starts before instructions are finished and continue observation (Correct answer)
Stop the test, rescore from zero, and restart instructions
End the test and note the suspect was uncooperative
Tell the suspect to stop and not score a clue since instructions weren't complete

Correct answer: Score a clue for starts before instructions are finished and continue observation

Starting before being told to do so is one of the eight scored clues for the Walk-and-Turn test; the officer scores it and continues observing.

Question 12: If an officer cannot remember a specific detail from the field sobriety test during testimony, the best practice is to:

State the detail from memory even if uncertain
Ask to review the arrest report or notes taken at the time (Correct answer)
Fabricate a plausible detail
Decline to answer entirely

Correct answer: Ask to review the arrest report or notes taken at the time

Officers may refresh their recollection by reviewing contemporaneous reports or notes, which is legally permissible during testimony.

Question 13: During testimony, the defense produces a video of the field sobriety tests. The officer should:

Object to any video evidence
Refuse to watch the video in court
Welcome the video and use it to reinforce or clarify observations already documented in the report (Correct answer)
Claim the video is inauthentic without reviewing it

Correct answer: Welcome the video and use it to reinforce or clarify observations already documented in the report

Officers should review video evidence and use it as an opportunity to correlate recorded observations with their written documentation.

Question 14: Defense counsel asks: 'Isn't it true that innocent medical conditions can cause HGN?' The officer's most accurate response is:

Yes, certain medical conditions can cause nystagmus, which is why officers are trained to screen for them (Correct answer)
Only DUI suspects have nystagmus
No, HGN is always caused by alcohol
The question is irrelevant to the case

Correct answer: Yes, certain medical conditions can cause nystagmus, which is why officers are trained to screen for them

Officers are trained to identify medical or other non-alcohol causes of nystagmus, and acknowledging this demonstrates thorough training.

Question 15: When a motorist is stopped at a sobriety checkpoint, which constitutional protection is most directly at issue?

Fifth Amendment double jeopardy
Second Amendment right to bear arms
Fourth Amendment protection against unreasonable seizure (Correct answer)
First Amendment free speech

Correct answer: Fourth Amendment protection against unreasonable seizure

Checkpoints are Fourth Amendment seizures; the Supreme Court upheld them in Michigan Dept. of State Police v. Sitz as reasonable given public safety interests.

Question 16: Why must the HGN stimulus be held at maximum deviation for a minimum of four seconds?

To ensure the subject is not blinking excessively
To allow the pupil to fully dilate
To distinguish voluntary nystagmus from alcohol-induced nystagmus (Correct answer)
To allow the officer to estimate the angle of deviation

Correct answer: To distinguish voluntary nystagmus from alcohol-induced nystagmus

Holding for four seconds allows the officer to confirm that the nystagmus is distinct and sustained rather than a brief, voluntary eye movement.

Question 17: When an officer's SFST report omits that the suspect was wearing high-heeled shoes during the Walk-and-Turn test, this constitutes:

An admissible inference
Exculpatory evidence suppression (Correct answer)
A minor clerical error
Standard administrative discretion

Correct answer: Exculpatory evidence suppression

Omitting factors that could explain poor performance suppresses potentially exculpatory evidence.

Question 18: Which environmental condition most significantly affects the reliability of the Walk-and-Turn test?

Daytime versus nighttime administration
Wind speed above 10 mph
An uneven or sloped surface (Correct answer)
The suspect's clothing type

Correct answer: An uneven or sloped surface

NHTSA requires a reasonably dry, hard, level, non-slippery surface; uneven or sloped surfaces compromise test validity.

Question 19: During HGN testing, at what angle from center should the officer begin checking for Lack of Smooth Pursuit?

Directly at center
10 degrees
45 degrees
20 degrees (Correct answer)

Correct answer: 20 degrees

The officer begins moving the stimulus from center and checks for Lack of Smooth Pursuit as the eye tracks through the full range of motion.

Question 20: A 'per se' DUI law means that a driver can be convicted because:

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

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 21: Which information is required on the standard SFST scoring sheet but is NOT typically found in a supplemental narrative report?

Individual clue-by-clue checkboxes for each standardized test (Correct answer)
The location of the traffic stop
Subject's date of birth
Officer's printed name and badge number

Correct answer: Individual clue-by-clue checkboxes for each standardized test

Standardized scoring sheets use individual clue checkboxes for systematic recording, while narrative reports describe observations in prose rather than checkbox format.

Question 22: When the officer is observing the suspect perform the One-Leg Stand and the suspect hops to maintain balance, what clue is scored?

Hopping (Correct answer)
Sways while balancing
Puts foot down
Raises arms

Correct answer: Hopping

Hopping is one of the four scored clues on the One-Leg Stand test and is scored when the suspect hops on the standing foot.

Question 23: What does BAC stand for in the context of DUI enforcement?

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

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 24: What role does self-assessment play in SFST professional development?

It allows practitioners to identify personal skill gaps and seek targeted improvement proactively (Correct answer)
It is only required for officers with prior disciplinary history
It is considered biased and discouraged in professional settings
It replaces formal recertification requirements

Correct answer: It allows practitioners to identify personal skill gaps and seek targeted improvement proactively

Self-assessment enables practitioners to identify areas where their technique may have drifted or weakened, allowing them to seek targeted refresher training proactively.

Question 25: Alcohol-induced nystagmus occurs primarily because alcohol impairs the function of which part of the brain?

Hypothalamus
Cerebral cortex
Cerebellum (Correct answer)
Temporal lobe

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 26: What is the significance of documenting the subject's statement 'I only had two beers' in an SFST report?

It proves the subject is not impaired and should trigger test termination
It is inadmissible hearsay and should be omitted from the report
It legally limits prosecution to only alcohol-related charges
It is an admission that may be compared to SFST performance and BAC evidence (Correct answer)

Correct answer: It is an admission that may be compared to SFST performance and BAC evidence

The subject's self-reported alcohol consumption is a relevant admission that can be contrasted with observed clues and chemical test results during prosecution.

Question 27: Under the Fourth Amendment, what standard must an officer meet before conducting a traffic stop?

Probable cause to believe a crime occurred
Reasonable articulable suspicion of a violation (Correct answer)
Beyond reasonable doubt
Preponderance of evidence

Correct answer: Reasonable articulable suspicion of a violation

Traffic stops require only reasonable articulable suspicion, a lower standard than probable cause.

Question 28: 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?

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

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

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

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 30: In DUI investigations, the Widmark formula is used to:

Calculate the minimum number of drinks that impair driving ability
Estimate a subject's BAC based on the amount of alcohol consumed, body weight, and elapsed time (Correct answer)
Measure how food consumption reduces peak BAC
Determine the rate at which BAC naturally decreases per hour

Correct answer: Estimate a subject's BAC based on the amount of alcohol consumed, body weight, and elapsed time

The Widmark formula estimates theoretical BAC by factoring in the amount of alcohol consumed, the individual's body weight and gender factor (r), and time elapsed since drinking began.

Question 31: Which organ is primarily responsible for metabolizing alcohol in the human body?

Liver (Correct answer)
Kidneys
Pancreas
Stomach

Correct answer: Liver

The liver is the primary organ responsible for metabolizing approximately 90–95% of consumed alcohol through enzymatic processes.

Question 32: An officer who arrests a sober driver based solely on a medical condition that mimics intoxication may face civil liability under:

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

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 33: When administering the OLS test, what should the officer do if the suspect begins counting faster than one number per second?

Allow it to continue — counting speed is not a clue
Score it as an additional clue for non-compliance
Stop the test and restart with clearer instructions
Remind the suspect to count at one number per second (Correct answer)

Correct answer: Remind the suspect to count at one number per second

The officer should remind the suspect to count at the instructed pace to ensure the test is properly timed, as 30 seconds is the standard duration.

Question 34: Under most U.S. zero-tolerance laws, drivers under the age of 21 may be charged with DUI at a BAC of:

0.02% or higher (Correct answer)
0.04% or higher
0.10% or higher
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 35: Which Supreme Court case established that the SFST battery is scientifically reliable and admissible in court?

Daubert v. Merrell Dow Pharmaceuticals (Correct answer)
National Highway Traffic Safety Administration v. Landry
Miranda v. Arizona
Terry v. Ohio

Correct answer: Daubert v. Merrell Dow Pharmaceuticals

Daubert v. Merrell Dow established the federal standard for admissibility of scientific evidence, which courts apply to SFST results.

Question 36: Which of the following should be included when documenting a subject's divided attention during the pre-test interview?

The make and model of the subject's vehicle
The officer's badge number and shift assignment
Observations of the subject's ability to simultaneously listen and respond (Correct answer)
The subject's social security number

Correct answer: Observations of the subject's ability to simultaneously listen and respond

Pre-test interview documentation should capture divided attention indicators such as answering before questions are finished or failing to follow multi-step directions.

Question 37: How should an officer document a subject who stops and restarts the Walk-and-Turn test without being told to?

Restart the test from the beginning and document only the second attempt
Note it as a 'stops while walking' clue, which is one of the 8 standardized WAT clues (Correct answer)
Ignore it if the subject successfully completes the test afterward
Record it as a separate, unofficial observation outside the scoring form

Correct answer: Note it as a 'stops while walking' clue, which is one of the 8 standardized WAT clues

Stopping while walking is one of the 8 standardized Walk-and-Turn clues and must be documented on the scoring sheet regardless of whether the subject recovers.

Question 38: During court testimony, a defense attorney asks why the officer did not use a stopwatch during OLS. What is the correct NHTSA-recommended response?

A stopwatch is optional; the subject's count controls timing
Officers are trained to estimate 30 seconds without equipment
NHTSA recommends using a watch or other timing device to measure the 30-second period (Correct answer)
OLS is purely observational and requires no timing

Correct answer: NHTSA recommends using a watch or other timing device to measure the 30-second period

NHTSA recommends that officers use a timing device to accurately measure the 30-second OLS period.

Question 39: During the Walk-and-Turn test, a suspect stops walking midway through the first nine steps. The officer should:

Immediately score a clue and ask the suspect to restart
End the test and note the inability to complete
Score a clue for stopping while walking and allow the suspect to continue (Correct answer)
Offer a second attempt without scoring the first

Correct answer: Score a clue for stopping while walking and allow the suspect to continue

Stopping while walking is a scorable clue, and the officer allows the suspect to continue to gather additional observations.

Question 40: What is a nosocomial infection?

A childhood disease
A genetic condition
An infection acquired in a healthcare facility (Correct answer)
A respiratory infection

Correct answer: An infection acquired in a healthcare facility

Nosocomial (healthcare-associated) infections are acquired during the course of receiving medical treatment in a healthcare facility, not present at admission.

Question 41: Which study approach is most effective for One Leg Stand material?

Passive re-reading of notes
Active recall with practice questions (Correct answer)
Studying for very long sessions without breaks
Highlighting all text

Correct answer: Active recall with practice questions

Active recall through practice questions is the most effective study method, as it strengthens memory retrieval pathways.

Question 42: Approximately how long does it take the average adult liver to metabolize one standard drink?

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

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 43: During the OLS instruction phase, the officer demonstrates the test while giving instructions. What is the primary purpose of this demonstration?

To ensure the subject understands what is required (Correct answer)
To intimidate the subject
To satisfy a legal requirement before arrest
To record baseline balance ability

Correct answer: To ensure the subject understands what is required

The demonstration during instructions ensures the subject clearly understands the task, reducing grounds for later challenge.

Question 44: Why must the officer's opinion of impairment be stated separately from the SFST clue counts in the report?

Mixing opinion with clue counts violates chain-of-custody rules
Opinion statements are reserved for toxicology lab technicians only
NHTSA prohibits officers from expressing opinions in written reports
Separating them distinguishes objective findings from professional interpretation, strengthening the report's credibility (Correct answer)

Correct answer: Separating them distinguishes objective findings from professional interpretation, strengthening the report's credibility

Clearly separating objective clue observations from the officer's professional opinion allows the court to evaluate both the data and the professional interpretation independently.

Question 45: Who typically accredits SFST certification programs?

International Law Enforcement Association
State licensing boards
Local government agencies
National Highway Traffic Safety Administration (NHTSA) (Correct answer)

Correct answer: National Highway Traffic Safety Administration (NHTSA)

The National Highway Traffic Safety Administration (NHTSA) is the federal agency responsible for developing, standardizing, and promoting the SFST curriculum and guidelines. NHTSA provides the foundational training materials and sets the standards for SFST certification programs across the United States. This ensures consistency, scientific validity, and legal defensibility in the administration of these tests nationwide.

Question 46: Vertical Gaze Nystagmus (VGN) is typically associated with BAC levels at or above:

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

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 47: In the One-Leg Stand test, what is the maximum time the officer should observe the suspect before stopping the test?

20 seconds
30 seconds (Correct answer)
25 seconds
45 seconds

Correct answer: 30 seconds

The One-Leg Stand test is timed for 30 seconds; the officer counts aloud and stops the test at that point.

Question 48: Which of the following is a legal requirement for administering SFSTs?

Both B and C (Correct answer)
The officer must have probable cause to suspect impairment
The subject must voluntarily agree to take the tests
The officer must inform the subject of the potential legal consequences of refusal

Correct answer: Both B and C

For SFSTs to be legally sound, an officer must first have probable cause to suspect impairment before requesting the tests. Additionally, in many jurisdictions, officers are required to inform the subject of the potential legal consequences of refusing to take the tests, such as administrative license suspension. Both these requirements ensure due process and the lawful collection of evidence, making the test results admissible in court.

Question 49: 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
Score 'incorrect number of steps' as one clue (Correct answer)
Score each extra step as a separate clue
Do not score it because more steps indicate more coordination

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

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

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.

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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