What Can Make a New Hampshire Field Sobriety Test Unreliable?

A New Hampshire field sobriety test can be less reliable when roadside conditions interfere with balance or visibility, when you have a medical or physical limitation, when instructions are unclear, or when the officer does not follow the standardized testing procedure. Field sobriety tests do not directly measure your blood alcohol concentration. They are observational tools used as part of a DWI investigation, so the circumstances surrounding the tests can affect how much weight the results deserve.

Tenn And Tenn, PA represents people facing DWI allegations in Manchester and throughout New Hampshire. A defense review can compare the police report with body-camera footage, cruiser video, medical information, weather and road conditions, and the way each roadside exercise was explained, demonstrated, scored, and recorded.

Poor performance on a field sobriety test does not automatically establish impairment. The test results should be considered with the rest of the evidence in your case.

A field sobriety test can be useful evidence without being a direct measurement of your blood alcohol concentration. The conditions and administration still matter.

What Are Field Sobriety Tests in a New Hampshire DWI Investigation?

During a suspected DWI investigation, an officer may ask you to perform roadside exercises intended to help evaluate balance, coordination, divided attention, and eye movement. The three standardized field sobriety tests used in the NHTSA testing battery are:

• Horizontal gaze nystagmus, or HGN
• Walk-and-turn
• One-leg stand

During the HGN test, the officer watches your eyes while you follow a moving stimulus. During the walk-and-turn, you are instructed to take heel-to-toe steps, complete a turn, and return along a line. During the one-leg stand, you are instructed to balance on one foot while counting for a period of time.

These are not laboratory tests. Their value depends on observation, instructions, physical performance, scoring, and the circumstances in which the exercises occur.

New Hampshire RSA 265-A:2 allows the State to pursue a DWI charge based on alleged impairment or a qualifying alcohol concentration. Field sobriety performance may be part of the evidence used during the investigation and in a later case, but the exercises do not directly produce a chemical alcohol concentration.

For more information about roadside testing in New Hampshire, visit:

https://www.tennandtenn.com/new-hampshire-field-sobriety-tests/

Poor Road or Weather Conditions Can Affect Your Performance

Field sobriety tests are often conducted on a roadside rather than in a controlled indoor setting. Surface, lighting, weather, and traffic conditions can affect the way you perform.

You may be asked to stand or walk on pavement that is:

• Sloped
• Cracked
• Wet
• Icy
• Gravel-covered
• Uneven
• Narrow or close to moving traffic

Rain, snow, wind, cold temperatures, darkness, glare, flashing emergency lights, and nearby traffic can also affect concentration, visibility, footing, or balance.

NHTSA recognizes that standardized field sobriety tests are not always administered under ideal roadside conditions. Less-than-ideal conditions do not automatically make a test invalid, but they can affect the evidentiary weight given to the results.

Video can be especially useful when road or weather conditions are disputed. Body-camera or cruiser footage may show whether the testing area was level, whether a visible line was available, how close traffic passed, and whether weather or lighting affected your footing or ability to follow instructions.

Physical Injuries and Medical Conditions May Affect Field Sobriety Tests

You can have difficulty with balance, walking, standing, or eye movement for reasons unrelated to alcohol or drugs.

Physical conditions that may matter can include problems involving your:

• Knees
• Ankles
• Hips
• Back
• Feet
• Balance
• Neurological function

An older injury may become more noticeable when you are asked to stand in an unusual position or balance on one leg beside a roadway.

Medical or visual conditions may also be relevant when HGN or other observations are used as evidence. The significance of a condition depends on the facts, the nature of the condition, and the available documentation.

A defense review may compare medical records with the police report and available video. The question is whether a documented condition provides a credible explanation for observations that the officer associated with impairment.

Footwear and Clothing Can Change the Testing Conditions

Shoes and clothing can affect a roadside exercise that depends on balance, traction, and precise foot placement.

High heels, heavy boots, loose shoes, footwear with limited traction, or other unsuitable shoes can change the way you walk or balance. Bulky winter clothing can also restrict movement.

The officer may address footwear before testing, but the details still matter. Video may show what you were wearing, whether you were given an opportunity to remove unsuitable footwear, and whether the surface was reasonably safe for the test.

Fatigue, Stress, and Distraction Can Affect Performance

A police stop can create stress, and a driver may also be tired, distracted by traffic, cold, or focused on understanding several instructions at once.

Standardized roadside exercises require you to listen, remember multiple steps, hold a particular position, and perform a physical task while being observed. A mistake may be recorded as a clue even when another explanation is possible.

A careful review should consider whether fatigue, stress, distraction, environmental conditions, or difficulty hearing the instructions could have affected what the officer observed.

Unclear Instructions or Demonstrations Can Affect the Result

Standardized field sobriety tests are designed to be administered in a standardized manner. Instructions and demonstrations matter because you need to understand the task before you can perform it as requested.

A defense review may ask:

• Did the officer explain the complete test before evaluating your performance?
• Did the officer demonstrate the required stance, steps, turn, or counting method?
• Did you ask a question or appear confused?
• Did the officer interrupt, restart, or change the instructions?
• Did traffic noise or another officer interfere with communication?
• Did the officer begin scoring before the instructions were complete?
• Did the officer count conduct as a clue when the instruction itself was unclear?

Video can provide a more complete record than a short written summary. It can show the timing, wording, demonstration, interruptions, and your response to the officer’s directions.

Improper Scoring Can Overstate What Happened

Standardized field sobriety testing uses specific clues that trained officers are taught to observe. The police report may summarize those clues, while video may show the actual performance.

A report may state that you:

• Stepped off the line
• Used your arms for balance
• Started before being told to begin
• Swayed
• Put your foot down
• Took the wrong number of steps
• Made an improper turn

The video may support the written account, show the event differently, or reveal circumstances that the report does not describe.

The comparison matters because a written report is only one record of the roadside encounter. A defense attorney can examine whether the officer identified the correct clue, applied the scoring criteria as trained, and described the performance accurately.

HGN Testing Requires Careful Administration

The horizontal gaze nystagmus test differs from the walk-and-turn and one-leg stand because it focuses on eye movement rather than balance.

During HGN testing, the officer moves a stimulus in front of your eyes and watches for specific clues. The value of the evidence can depend on whether the officer followed the testing procedure, including the position and movement of the stimulus and the timing of the test.

Lighting, distractions, officer training, and documented medical or visual issues may also become relevant depending on the facts.

HGN evidence should be reviewed together with the rest of the roadside investigation. It does not directly provide a blood alcohol concentration.

Field Sobriety Tests Are Only One Part of the DWI Evidence

A New Hampshire DWI investigation can involve more than field sobriety testing. Police may also rely on:

• Driving behavior
• Statements made during the stop
• Physical observations
• Crash evidence
• Witness accounts
• Body-camera or cruiser video
• A preliminary breath test, if one was requested and administered
• Post-arrest breath, blood, or other chemical-test evidence

The broader record can support or weaken the officer’s interpretation of the roadside tests. Video may show signs that support the police report. It may also show that you walked normally, spoke clearly, followed directions, or performed differently from the written description.

For an overview of New Hampshire DWI defense issues, visit:

https://www.tennandtenn.com/new-hampshire-dwi-lawyers/

For information about what can happen after an arrest, visit:

https://www.tennandtenn.com/after-a-dwi-arrest-in-new-hampshire/

If a roadside breath screening test was requested, learn how that test differs from field sobriety exercises and post-arrest chemical testing here:

https://www.tennandtenn.com/preliminary-breath-testing-in-new-hampshire/

What Should You Preserve After a DWI Arrest?

If field sobriety test reliability may become an issue in your case, preserving records can help your attorney evaluate the roadside encounter.

Keep:

• Police paperwork
• Court documents
• Towing records
• New Hampshire Department of Safety documents
• Relevant medical records
• Photographs of injuries or physical limitations
• Receipts or records that may help establish timing
• Messages or location records that may help establish a timeline

Write down what you remember about:

• The testing location
• Lighting
• Weather
• Road or shoulder conditions
• Your footwear and clothing
• Injuries or medical conditions
• The officer’s instructions
• Any demonstrations
• Questions you asked
• Your performance
• Statements made before, during, or after testing

Do not assume that the police report includes every detail of the roadside setting. Your own timely notes may help identify facts that should be compared with video or other records.

Speak With a New Hampshire DWI Lawyer

A field sobriety test should be evaluated in context rather than treated as a direct measure of impairment. Road conditions, weather, health, footwear, fatigue, instructions, scoring, video, and officer training may all affect how the evidence is interpreted.

Tenn And Tenn, PA represents people facing DWI allegations in Manchester and throughout New Hampshire. The firm uses a personalized, client-centered approach and can review the traffic stop, roadside testing, available video, chemical-test evidence, medical information, and other facts that may affect your case.

Tenn And Tenn, PA offers consultations at no charge. Call 603-614-5055 to discuss your situation.

https://www.tennandtenn.com/contact-us/

This article is for informational purposes only and is not legal advice. Reading this article does not create an attorney-client relationship. Consult an attorney about your specific situation.