Challenging Field Sobriety Tests in a New Jersey DWI Case

Field sobriety tests often become some of the most important evidence in a New Jersey DWI prosecution. After a traffic stop, police may ask the driver to perform roadside exercises to help determine whether there is probable cause to make a DWI arrest.

But field sobriety tests are not infallible.

Performance can be affected by improper instructions, age, weight, medical conditions, footwear, road conditions, weather, anxiety, fatigue, and whether the officer actually followed standardized testing procedures.

A DWI defense attorney should therefore examine more than whether the police report says the driver “failed.” The important questions are how the tests were administered, whether the driver was physically suited to perform them, what clues were actually observed, and what the body-camera or dash-camera footage shows.

For a complete overview of New Jersey DWI law, defenses, penalties, and testing issues, visit our New Jersey DWI Lawyer and Defense Guide.

Key Takeaways About Field Sobriety Tests

NHTSA recognizes three standardized tests: HGN, Walk-and-Turn, and One-Leg Stand.
NHTSA materials recognize that drivers over age 65 and people with certain physical conditions may have difficulty performing the physical balance tests.
NHTSA specifically recognizes that people 50 pounds or more overweight may have difficulty performing the One-Leg Stand.
HGN is treated differently from the physical tests under New Jersey law.
Under State v. Doriguzzi, 334 N.J. Super. 530 (App. Div. 2000), HGN cannot simply be used as substantive scientific proof of intoxication without the required scientific foundation.
Police reports should be compared against body-camera and dash-camera footage whenever available.
Field sobriety evidence can be challenged when evaluating probable cause and, depending on the circumstances, through a motion to suppress evidence.

What Are Standardized Field Sobriety Tests?

The National Highway Traffic Safety Administration, commonly known as NHTSA, recognizes a three-test standardized field sobriety battery:

Test	What Police Evaluate	Important Defense Issues
Walk-and-Turn	Balance, heel-to-toe walking, following instructions, turn	Age, leg/back/inner-ear problems, footwear, surface, instructions
One-Leg Stand	Swaying, arms for balance, hopping, putting foot down	Age, physical limitations, substantial excess weight, surface
Horizontal Gaze Nystagmus (HGN)	Involuntary eye movements	Proper administration, scientific admissibility, State v. Doriguzzi

NHTSA continues to publish detailed participant, instructor, and refresher materials governing how officers are trained to administer SFSTs. (NHTSA)

The word standardized is important. The tests are supposed to be administered according to a specific protocol. If an officer significantly departs from that protocol, the defense can question the reliability and weight of the resulting observations.

The Walk-and-Turn Test

The Walk-and-Turn is intended to be a divided-attention test.

The driver is generally instructed to stand heel-to-toe, listen to the officer’s instructions, keep the arms at the sides, take nine heel-to-toe steps, perform a prescribed turn, and take nine steps back.

Police are trained to look for clues such as:

inability to maintain balance during the instructions;
starting before the instructions are completed;
stopping while walking;
failing to touch heel-to-toe;
stepping off the line;
using the arms for balance;
making an improper turn; and
taking the wrong number of steps.

The defense should examine the actual performance rather than accept a report that simply says the person “failed.”

NHTSA Limitation: Age and Physical Conditions

NHTSA training materials recognize that the Walk-and-Turn can be more difficult for certain individuals, including people over 65 years old and people with back, leg, or inner-ear problems.

That does not mean the test is automatically invalid for an older person. It means those factors should be considered when deciding whether small balance errors actually demonstrate alcohol impairment.

For example, if a 72-year-old driver completes all eighteen steps without falling but briefly raises an arm or leaves several small heel-to-toe gaps, age and physical ability may provide an important alternative explanation.

Learn What Can Affect the Walk-and-Turn Test

The defense should examine the conditions under which the Walk-and-Turn was performed.

Was the surface level?
Was there a visible line?
Was the road shoulder sloped?
Was the pavement wet, icy, cracked, or covered with gravel?
Was traffic passing nearby?
Were emergency lights flashing toward the driver?
Was the driver wearing difficult footwear?
Did the driver report knee, hip, ankle, back, neurological, or balance problems?
Did the officer correctly demonstrate the test?
Did the officer give complete instructions?

The One-Leg Stand Test

The One-Leg Stand is another divided-attention test.

The driver is generally instructed to stand with the arms at the sides, raise one foot approximately six inches from the ground, keep the legs straight, look at the elevated foot, and count aloud until told to stop.

Officers commonly look for four clues:

swaying;
using the arms for balance;
hopping; and
putting the foot down.

Again, the real issue is not whether the officer labeled the result a “failure.” The defense should determine what actually happened and whether another explanation exists for the movement.

NHTSA Limitation: Drivers Over 65 and People 50+ Pounds Overweight

The One-Leg Stand has particularly important physical limitations.

NHTSA training materials recognize that people may experience difficulty with the test if they are:

over 65 years old;
suffering from back problems;
suffering from leg problems;
suffering from inner-ear problems; or
50 pounds or more overweight.

This is especially significant because the One-Leg Stand asks a driver to balance on one leg for an extended period.

A substantially overweight person may sway, raise an arm, or put a foot down even when completely sober.

Being 50 pounds overweight does not automatically invalidate the test. But it is a recognized physical factor that may provide an alternative explanation for movements the officer records as evidence of impairment.

Learn Why Age and Weight Matter

Imagine a 70-year-old driver being asked to stand on one leg for approximately thirty seconds on the shoulder of a road.

Or imagine a person who is substantially overweight performing the same exercise on uneven pavement.

If that person sways or briefly lowers a foot, those movements may be recorded as standardized clues of intoxication.

But those same movements may also result from age, body weight, balance limitations, orthopedic problems, or the testing environment.

The defense should consider:

Age
Height and weight
Body type
Knee, hip, ankle, or back problems
Prior surgery
Neurological conditions
Inner-ear disorders
Whether the officer asked about physical limitations
Whether those limitations appear on the video

Horizontal Gaze Nystagmus and State v. Doriguzzi

The Horizontal Gaze Nystagmus test, commonly called HGN, is different from the Walk-and-Turn and One-Leg Stand.

During HGN testing, the officer typically instructs the driver to follow a stimulus, such as a pen or fingertip, with their eyes while keeping the head still. The officer watches for involuntary jerking of the eyes called nystagmus.

NHTSA includes HGN as one of the three standardized field sobriety tests. However, New Jersey courts do not treat HGN the same way as ordinary physical coordination tests.

Key New Jersey Case: State v. Doriguzzi

The leading New Jersey case is: State v. Doriguzzi, 334 N.J. Super. 530 (App. Div. 2000).

In Doriguzzi, the municipal court and Law Division relied in part on the defendant’s HGN performance in finding him guilty of DWI.

The Appellate Division reversed. It held that HGN is scientific evidence and declined to permit the test to be used as substantive proof of intoxication without an adequate scientific reliability foundation.

The court also made an important distinction: HGN may have a role during the police investigation in determining probable cause, but that is different from using it at trial as substantive proof that the defendant was intoxicated.

Later New Jersey appellate authority has continued to recognize that distinction. (State v. O’Neill)

Why Doriguzzi Matters in a DWI Defense

An officer may write that the defendant “failed HGN” and treat the result as strong evidence of intoxication.

But under New Jersey law, the defense should examine how the State is attempting to use that evidence.

There is an important difference between:

HGN as one part of an officer’s probable-cause investigation

and

HGN as scientific proof that the defendant was intoxicated at trial.

That distinction can matter significantly in a New Jersey DWI prosecution.

Learn How to Challenge the HGN Test

Because HGN involves physiological observations, proper administration is especially important.

The defense should examine whether:

The officer checked for equal pupil size
The officer checked for resting nystagmus
Both eyes tracked equally
The stimulus was held at the proper distance
The stimulus was moved at the proper speed
The driver was instructed to keep the head still
The officer could actually see the driver’s eyes clearly
Emergency lights or other visual distractions were present
The officer followed the standardized training protocol

The fact that an officer has received SFST training does not establish that every roadside HGN test was administered correctly.

Was the Officer Properly Trained?

The reliability of field sobriety evidence also depends on the officer’s training and administration.

The defense may examine:

when the officer received initial SFST training;
whether refresher training was completed;
which version of the NHTSA manual was used;
whether the officer correctly remembered the protocol;
whether the instructions matched the standardized procedures;
and whether the officer departed from the training during the actual stop.

NHTSA maintains formal SFST training and refresher curricula for law enforcement officers. (NHTSA)

A standardized test becomes less persuasive when the officer substantially departs from the standardized procedure.

Learn How Bad Instructions Can Produce an Inaccurate Result

Yes. Instructions are part of the standardized testing process.

If an officer records that a driver “started too soon,” the video should show whether the driver was clearly told not to begin until instructed.

If the officer says the driver made an improper turn, the defense should determine whether the officer properly demonstrated the turn.

If the officer records that the driver stepped off the line, the defense should determine whether a meaningful line was actually available.

Confusing, incomplete, or incorrectly demonstrated instructions can affect performance and should be considered before a mistake is treated as evidence of intoxication.

Medical and Physical Conditions Can Mimic Poor SFST Performance

Physical conditions can affect roadside testing even when alcohol is not responsible.

Potential issues include:

knee injuries;
ankle injuries;
hip problems;
back conditions;
arthritis;
neuropathy;
vertigo;
inner-ear disorders;
neurological conditions;
prior orthopedic surgery;
balance disorders;
weakness;
chronic pain; and
mobility limitations.

Where appropriate, medical records may provide objective evidence that the condition existed before the DWI arrest.

The important question is not simply whether the defendant has a diagnosis. It is whether the condition provides a legitimate explanation for what the police characterized as impaired coordination.

This issue will also be addressed in greater depth on our separate page covering medical and physical conditions that can affect a New Jersey DWI investigation.

Learn How Road Conditions, Weather, or Footwear Affect SFSTs?

Yes. Field sobriety testing frequently takes place under less-than-ideal roadside conditions.

Potential problems include:

Darkness
Flashing patrol lights
Passing traffic
Cold temperatures
Rain
Snow
Wind
Uneven pavement
Gravel
Sloped shoulders
Potholes
Limited testing space
High heels
Work boots
Sandals
Loose-fitting or damaged footwear

These circumstances do not automatically invalidate a field sobriety test, but they can affect balance and concentration and should be considered when evaluating the significance of the driver’s performance.

Learn How Anxiety Can Affect Field Sobriety Tests

Yes. A roadside DWI investigation can be extremely stressful.

A driver may be standing beside a road late at night with emergency lights flashing, traffic passing, multiple officers watching, and the possibility of arrest becoming obvious.

Anxiety can cause:

Trembling
Nervous movements
Difficulty concentrating
Rushed answers
Confusion
Physical tension

Those symptoms can sometimes be characterized as signs of intoxication even though nervousness itself does not establish DWI.

Body-Camera Footage Can Be Critical

Field sobriety testing is one of the areas where body-worn camera and dash-camera evidence can be particularly valuable.

The police report may say the driver:

nearly fell;
swayed dramatically;
stepped off the line repeatedly;
failed to understand instructions;
raised their arms for balance;
stopped walking; or
could not complete the exercises.

The video may confirm those statements.

But sometimes it shows something very different.

A driver may complete most of the tests successfully even though the report emphasizes a handful of technical mistakes.

Video may also reveal:

improper instructions;
poor testing conditions;
physical complaints;
difficult footwear;
interruptions;
or inconsistencies between what the officer wrote and what actually happened.

For a broader discussion, see our guide to challenging police reports using body-camera footage in New Jersey.

How If the Police Report Says I “Failed”?

The standardized field sobriety tests are based on individual clues, not simply a universal pass-or-fail determination.

For example, a driver may take all eighteen Walk-and-Turn steps without losing balance but leave small spaces between heel and toe.

The police report may nevertheless reduce the entire performance to the word “failed.”

The defense should instead determine:

Which clues were actually observed
Whether the clues were scored correctly
Whether the video confirms them
Whether physical limitations explain them
How much of the test the driver performed correctly

The actual performance is more informative than the label used in the police report.

Field Sobriety Tests and Probable Cause to Arrest

Field sobriety performance often becomes a major part of the officer’s probable-cause determination.

But probable cause is based on the totality of the circumstances, not simply one roadside exercise.

The defense should examine the entire encounter.

For example:

Did the driver pull over normally?
Was their speech clear?
Did they retrieve their license and documents normally?
Did they exit the vehicle without difficulty?
Did they walk normally before the testing began?
Did they understand the officer’s questions?
Were there meaningful signs of alcohol consumption?
Did they perform most portions of the SFSTs correctly?

These details can provide important context that may be missing from a police report.

Can Field Sobriety Tests Be Challenged at a Suppression Hearing?

Yes.

Depending on the circumstances, the defense may challenge whether police had sufficient grounds to expand a routine motor vehicle stop into a DWI investigation or whether there was probable cause to arrest the driver after the testing.

These issues may be raised through a motion to suppress evidence.

There can be several separate constitutional questions:

Was the original traffic stop lawful?
Did police develop sufficient grounds to prolong the stop and begin a DWI investigation?
Did the officer ultimately have probable cause to make the arrest?

For more information about the first issue, see our guide to challenging the traffic stop in a New Jersey DWI case.

Can You Refuse Field Sobriety Tests in New Jersey?

Yes.

Roadside physical field sobriety tests should not be confused with the breath test requested after a DWI arrest.

New Jersey’s implied-consent law applies to chemical breath testing under N.J.S.A. 39:4-50.2, and refusal to submit to the required breath test can result in a separate charge under N.J.S.A. 39:4-50.4a.

The roadside Walk-and-Turn and One-Leg Stand are legally different.

There is no separate Title 39 refusal offense equivalent to Alcotest refusal merely because someone declines to perform those physical exercises.

However, declining SFSTs does not prevent an arrest. Police can still rely on other observations they believe establish probable cause.

The distinction between roadside SFSTs and the stationhouse breath test is therefore important.

Learn the Difference Between Field Sobriety Tests and the Alcotest?

No. Roadside field sobriety testing and stationhouse breath testing are different forms of evidence.

SFSTs are based primarily on officer observations of physical or physiological performance.

A breath test is scientific evidence intended to measure breath alcohol concentration.

Breath-test cases involve separate issues concerning:

Alcotest operation
Calibration
Maintenance
Required observation procedures
Operator training
Foundational documents
Scientific reliability

Those issues should be analyzed separately from roadside field sobriety testing.

Learn About Sobriety Tests in Drug DWI Cases

Field sobriety evidence can also become important when police suspect impairment from drugs rather than alcohol.

Drug DWI cases may rely on:

Driving observations
Physical appearance
Field sobriety tests
Statements
Toxicology evidence
Drug Recognition Expert evaluations
Other circumstantial evidence

Because there may not be a breath-alcohol result, the accuracy of the officer’s roadside observations can become particularly important.

What the Defense Should Review

When evaluating field sobriety evidence, a defense attorney should consider:

Police report
Body-camera footage
Dash-camera footage
Officer SFST training
NHTSA testing procedures
Exact test instructions
Testing surface
Weather
Lighting
Footwear
Driver age
Driver height and weight
Medical conditions
Prior injuries or surgeries
Physical complaints made during the stop
Whether the video matches the report
Whether probable cause actually existed

This is why a careful review of the entire roadside encounter is more useful than simply counting how many “clues” appear on a police worksheet.

Other Defense Issues in a New Jersey DWI Case

Field sobriety testing is only one part of a DWI prosecution.

Other potential defense issues may include:

the legality of the traffic stop;
breath-test evidence;
proof of operation;
medical conditions;
blood or urine testing;
drug-impairment evidence;
statements made to police;
chain-of-custody problems; and
video evidence that contradicts the police report.

Where scientific or physical evidence is involved, see our Chain of Custody & Evidence Audits in New Jersey guide.

For broader constitutional and evidentiary defenses, visit our Criminal Defense Strategies & Legal Tactics: A Statewide NJ Resource.

Frequently Asked Questions About Field Sobriety Tests in New Jersey

What are the three standardized field sobriety tests?

The NHTSA standardized battery consists of Horizontal Gaze Nystagmus, Walk-and-Turn, and One-Leg Stand. (NHTSA)

Can being over age 65 affect field sobriety testing?

Yes. NHTSA training materials identify age over 65 as a factor that may make the physical balance tests more difficult. It does not automatically invalidate a test, but it should be considered when evaluating the person’s performance.

Can being overweight affect the One-Leg Stand?

Yes. NHTSA training materials recognize that a person approximately 50 pounds or more overweight may have difficulty performing the One-Leg Stand. That may provide an alternative explanation for swaying, raising the arms for balance, hopping, or putting the foot down.

Can a bad knee, back problem, or inner-ear condition affect the tests?

Yes. NHTSA training materials recognize back, leg, and inner-ear problems as conditions that can make physical SFSTs more difficult.

Is HGN admissible as proof of DWI in New Jersey?

The principal New Jersey case is State v. Doriguzzi, 334 N.J. Super. 530, 760 A.2d 336 (App. Div. 2000). The Appellate Division held that HGN could not simply be used as substantive scientific proof of intoxication without an adequate scientific foundation, while recognizing that police may consider HGN in the probable-cause analysis.

Does “failing” a field sobriety test prove DWI?

No. SFST observations are evidence, but the State must prove the DWI based on the admissible evidence as a whole. A police report’s characterization of a test as a “failure” does not itself establish guilt.

Can body-camera footage help challenge the tests?

Yes. Video can show the instructions, testing environment, footwear, physical complaints, actual performance, and whether the officer’s report accurately describes the roadside encounter. See our body-camera footage defense guide.

Can field sobriety testing be challenged before trial?

Yes. Depending on the circumstances, the defense may challenge the continuation of the stop, probable cause for arrest, or other police conduct through a motion to suppress evidence.

Is refusing field sobriety testing the same as refusing the Alcotest?

No. Refusing the required breath test is governed by New Jersey’s implied-consent statutes and can result in a separate refusal charge. The roadside physical exercises are legally distinct.

Learn More About New Jersey DWI Defense

Challenging field sobriety evidence is only one part of defending a DWI charge. A case may also involve an unlawful traffic stop, unreliable breath testing, proof of operation, medical issues, blood or urine evidence, drug impairment, or other constitutional and evidentiary problems.

For a complete overview of New Jersey DWI law, penalties, defenses, and the municipal court process, visit our New Jersey DWI Lawyer and Defense Guide.

Challenging Field Sobriety Test Evidence in New Jersey

Field sobriety tests can be persuasive evidence for prosecutors, but they should not be accepted at face value.

A proper DWI defense should examine whether the officer was trained, whether standardized procedures were followed, whether the driver was physically appropriate for the tests, whether age or weight affected performance, whether medical limitations were considered, whether the testing conditions were suitable, and whether police video supports the officer’s written conclusions.

HGN should also be evaluated separately because of the scientific-admissibility concerns addressed in State v. Doriguzzi.

William Proetta Criminal Law reviews police reports, body-camera and dash-camera recordings, officer training, NHTSA testing procedures, medical issues, and the totality of the roadside investigation when defending DWI charges in New Jersey.

If you have been charged with DWI, call (201) 793-8018 in Jersey City or (732) 659-9600 in Edison for a confidential consultation.