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Massachusetts takes drinking and driving very seriously. According to the state government, almost 8,000 people were arrested for OUI in 2024, and almost all of those arrests were made after the person failed a field sobriety test.
Field sobriety tests help police assess whether you’re impaired and do that using a series of coordination and attention-based exercises. That’s before a breathalyzer or blood test is even administered. Understanding what these tests involve, how accurate they are, and what your rights are during a stop can make a huge difference in your case.
Why Do Police Use Field Sobriety Tests During OUI Stops in Massachusetts?
Police use field sobriety tests to help determine whether there’s probable cause to suspect you’re under the influence.
If you’re pulled over because an officer suspects that you’re driving under the influence, these tests kick off the investigative phase. They’re usually conducted on the side of the road before you’re asked to take a breath or blood test. If you fail the breath/blood test, it will be reported to the Registry of Motor Vehicles (RMV). Officers are trained to watch for physical signs of impairment (think struggling for balance, slurring your speech, or seeming confused) that might support an arrest.
The tests can be surprisingly subjective. Any lack of balance or loss of footing may be taken as signs that you’ve been drinking, so it’s important to contact an attorney right away if you’ve been stopped.
Learn more about OUI defense in Worcester.
What Types of Standardized Field Sobriety Tests Are Used in MA OUI Cases?
Massachusetts police usually use three “standardized field sobriety tests” (SFSTs) approved by the National Highway Traffic Safety Administration (NHTSA).
These include:
- Horizontal Gaze Nystagmus (HGN): Evaluates your eye movement.
- Walk-and-Turn (WAT): Tests how coordinated you are and whether you can follow directions.
- One-Leg Stand (OLS): Assesses your balance and focus.
Combined, they gauge your divided attention, balance, and coordination. Officers look for clues (swaying, stepping off a line, or not following instructions) that may suggest that you’re impaired.
However, NHTSA studies show overall accuracy between 65% and 85%, meaning sober people can still fail. If you were given these tests, it’s smart to talk to a lawyer.
What Is the Horizontal Gaze Nystagmus (HGN) Test in OUI Investigations?
The HGN test involves following a moving object (pen, flashlight, etc.) with your eyes.
Officers check for involuntary eye jerking (nystagmus). They look for specific cues, including “lack of smooth pursuit”, “distinct jerking at maximum deviation”, and “onset of jerking before 45 degrees”. If they spot 4 or more clues out of 6, it tells them you’re likely impaired.
But there’s a catch. Medical conditions, fatigue, and too little light can affect results. The Massachusetts Supreme Judicial Court (SJC) has limited the admissibility of HGN test results unless supported by expert testimony.
What Is the Walk-and-Turn Test and How Is It Performed?
The walk-and-turn test requires you to take 9 heel-to-toe steps along a straight line, turn on one foot, and return the same way.
Officers watch for 8 clues, including starting before instructions finish, missing heel-to-toe contact, and stepping off the line. If they spot 2 or more, they may say you failed.
But real-world conditions (like uneven pavement or nerves) can make this tough. Shoes, weather, and physical issues matter, too. Don’t try to judge your performance alone. Get legal help to break it down.
What Does the One-Leg Stand Test Involve in Massachusetts?
The one-leg stand test requires you to lift one leg about six inches off the ground and count out loud for 30 seconds.
Officers look for 4 clues: swaying, using arms for balance, hopping, or putting your foot down. Just 2 can be enough to fail you. This test checks psychophysical abilities: coordination, balance, and attention.
However, age, injury, or even traffic noise can affect your results. If you struggled with this test, a local attorney can help determine why and whether it can be challenged.
Read more about police procedure errors in OUI stops.
Are Non-Standardized Field Sobriety Tests Common in Worcester OUI Cases?
Yes. Officers sometimes use non-standardized tests like reciting the alphabet backward, touching your nose, or counting by sevens.
These aren’t NHTSA-approved, and studies show their accuracy can be as low as 50–70%. Despite their limitations, they’re still used and can affect the officer’s decision about arresting you.
If you were asked to perform these, talk to a defense lawyer who can evaluate how those results fit into your case.
Read our guide to make sure you understand the OUI definition in Massachusetts.
Can You Refuse to Take Field Sobriety Tests in Massachusetts?
Yes, you can refuse field sobriety tests in Massachusetts without automatic penalties.
These tests aren’t covered by the state’s implied consent law, unlike breath tests. However, refusal can still influence the officer’s decision to arrest you.
If you declined, that choice could work in your favor (or against you) depending on how it’s presented. A defense attorney can help assess your next steps. Note that refusing a breath test can be held against you and does come with automatic penalties.
Learn more about refusing a breathalyzer in MA OUI.
How Accurate Are Field Sobriety Tests for Detecting Impairment in OUI?
Studies show field sobriety tests can be accurate, but only to a point.
When used together, NHTSA research says they’re 80–90% reliable in predicting blood alcohol content over the legal limit. Individually, HGN scores highest (77–88%), while OLS and WAT hover around 65–75%. None of those tests is foolproof, even in controlled settings.
What’s more, accuracy drops in real-world conditions. That’s why it’s so important to have an attorney review how your test was administered.
What Factors Can Cause Someone to Fail Field Sobriety Tests Without Being Impaired?
A lot of everyday factors can cause you to fail these tests, even if you’re completely sober, like weight, age, health conditions, etc.
The most likely factors that can fail you even if you’re sober include:
- Age or weight
- Medical conditions (like vertigo or inner ear issues)
- Injuries
- Anxiety or nervousness
- Poor lighting or uneven surfaces
Some studies estimate that 20 to 40% of sober drivers show signs of impairment under these conditions. If that happened to you, a skilled attorney can help prove it.
Learn about the penalties for OUI in Massachusetts.
How Do Field Sobriety Test Results Affect Your OUI Case in Court?
Field sobriety test results can be used as evidence, but they’re not bulletproof.
A good lawyer can challenge their validity by questioning how the test was given or interpreted. For example, if the officer didn’t follow protocol or if your medical issues weren’t considered, your results might be ruled unreliable.
Massachusetts courts use the Daubert standard to decide whether scientific evidence is admissible. That means these tests must meet specific reliability criteria.
Talk to a Worcester criminal defense attorney today.
Frequently Asked Questions About Field Sobriety Tests in MA OUI Cases
Should You Refuse Field Sobriety Tests If You’re Sober in Massachusetts?
You can legally refuse, and in some cases, it might be the smarter option. But every situation is different, so it’s wise to speak with a lawyer first.
What If You Fail a Field Sobriety Test Due to a Medical Condition or Injury?
These conditions can be used as part of your defense. Be sure to tell your attorney and provide any medical documentation.
Are Field Sobriety Tests Required by Law in Massachusetts OUI Stops?
No. They’re voluntary, and refusing them doesn’t carry the same consequences as refusing a breath test.
Can Field Sobriety Test Results Be Challenged in Court for Accuracy?
Absolutely. Lawyers often challenge how the test was administered, whether conditions were fair, and whether the officer followed proper guidelines.
How Do Field Sobriety Tests Differ for Marijuana OUI Versus Alcohol in MA?
FSTs are less reliable for detecting drug impairment. Massachusetts courts have ruled they can’t be used as definitive proof of marijuana impairment.
Learn more about OUI charges without driving in MA.