Field sobriety tests are some of the most misunderstood evidence in a Mississippi DUI case. People often treat them like a pass-or-fail exam. That is not the right way to think about them.
Roadside field sobriety exercises can matter, but they are not the same thing as the evidentiary chemical test under Mississippi's implied-consent law. And one test in particular, horizontal gaze nystagmus, or HGN, has a special rule in Mississippi.
The Short Answer
Mississippi DUI cases can involve roadside field sobriety exercises, officer observations, video, statements, driving behavior, chemical-test evidence, and refusal evidence. Walk-and-turn and one-leg-stand evidence may be used as ordinary observational evidence, but their weight depends on the facts.
HGN is different. In Young v. City of Brookhaven, the Mississippi Supreme Court treated HGN as scientific evidence and held that HGN cannot be used before the jury to prove intoxication or impairment. It may be used for probable-cause issues.
That means a DUI case does not automatically disappear just because HGN was mentioned, and it also means HGN should not be treated like ordinary balance-and-coordination evidence.
Field Sobriety Tests Are Not the Same as the Chemical Test
Mississippi's implied-consent statutes deal with chemical testing. Mississippi Code section 63-11-5 addresses chemical tests of breath, blood, or urine. Refusing an evidentiary chemical test can create separate legal consequences, and Mississippi Code section 63-11-41 makes evidence of a refusal admissible in a criminal action under the Implied Consent Law.
Roadside field sobriety exercises are different. Walk-and-turn, one-leg stand, and HGN are not breath, blood, or urine tests. They are roadside investigative tools that officers use while deciding whether they believe a DUI arrest is justified.
That distinction matters because people often ask, "Was I required to do field sobriety tests?" The safest public answer is this: field sobriety exercises are not the same as the post-arrest evidentiary chemical test governed by implied consent. But the practical effect of refusing roadside exercises can still depend on the facts of the stop, the officer's observations, and the probable-cause analysis.
For refusal and license issues tied to the evidentiary chemical test, see the separate guide to Mississippi DUI refusal and license consequences.
Walk-and-Turn and One-Leg Stand Evidence
Walk-and-turn and one-leg stand tests are usually offered as observations about balance, coordination, instruction-following, divided attention, and demeanor. They are not magic. They do not automatically prove guilt, and they do not automatically clear the case if a person appears to do well.
The weight of those tests can depend on:
- the instructions given by the officer;
- whether the instructions were demonstrated clearly;
- the surface where the test was performed;
- lighting, weather, traffic, and noise;
- footwear;
- age, weight, injury, or medical limitations;
- anxiety or confusion during the stop;
- whether the video matches the written report;
- and whether the officer's testimony is consistent with the rest of the evidence.
A person may have a medical, mobility, balance, or neurological reason for struggling with roadside tasks. That does not automatically defeat a DUI charge, but it can affect how much weight the evidence deserves.
Why HGN Is Different in Mississippi
HGN stands for horizontal gaze nystagmus. In simple terms, it is an eye-movement test. Officers use it to look for involuntary jerking of the eyes while a person follows a stimulus.
Mississippi treats HGN differently from ordinary balance-and-coordination evidence. In Young v. City of Brookhaven, 693 So. 2d 1355 (Miss. 1997), the Mississippi Supreme Court held that HGN is a scientific test. The Court also held that HGN was not generally accepted within the scientific community for use as scientific evidence to prove intoxication or impairment.
The practical public rule is:
- HGN is not admissible before the jury to prove intoxication or impairment.
- HGN may be used for probable-cause issues.
- HGN is not just another ordinary field sobriety test in Mississippi.
That rule should not be overstated. It does not mean every DUI case involving HGN gets dismissed. It means HGN has a limited use, and the defense should look carefully at whether the State is trying to use HGN for more than Mississippi law allows.
A DUI Case Can Exist Without a BAC Number
Another common misunderstanding is that a DUI case requires a breath-test number. It does not always work that way.
Mississippi recognizes impairment-based DUI proof. In Moore v. State, 154 So. 3d 12 (Miss. 2014), the Mississippi Supreme Court affirmed that a blood-alcohol level is not necessary when other sufficient evidence proves impairment under Mississippi Code section 63-11-30(1)(a). A prosecutor may try to prove impairment with facts such as:
- driving behavior;
- the reason for the stop;
- officer observations;
- odor of alcohol or other substances;
- speech, balance, and demeanor;
- admissions or statements;
- video;
- refusal evidence;
- possession or container evidence;
- and other surrounding circumstances.
That is why field sobriety evidence matters even when it does not decide the whole case. The State may use it as part of a larger story. The defense may challenge whether that story is reliable, complete, or consistent with the video and paperwork.
Video Can Help or Hurt Either Side
Video matters because it can cut through vague labels. A report may say "unsteady," but the video may show how the person actually walked, stood, spoke, listened, and responded. Sometimes video helps the defense. Sometimes it helps the State.
Useful questions include:
- Does the video show the instructions?
- Was the road level?
- Was traffic passing nearby?
- Could the person hear the officer?
- Did the officer demonstrate the test?
- Was the person wearing shoes that made the test harder?
- Did the officer mention medical problems?
- Does the video match the written report?
- Is the audio complete?
The answer is not always obvious from the report alone.
Common Mistakes After Field Sobriety Testing
The most common mistakes are practical:
- Assuming the tests decide the whole case. DUI cases are usually built from multiple pieces of evidence.
- Ignoring HGN. HGN has special limits in Mississippi and should be reviewed separately.
- Assuming no BAC means no case. The State may try to prove impairment without a test number.
- Failing to preserve video. Body-camera and dash-camera evidence can be important.
- Forgetting medical or physical limitations. Knee injuries, balance issues, eye conditions, medications, anxiety, fatigue, and footwear may matter.
- Entering a plea before reviewing the evidence. The report is not the same thing as the proof.
What a Lawyer Looks For
In a Mississippi DUI case involving field sobriety evidence, a lawyer will usually want to review:
- the citation or charging document;
- the officer's report;
- body-camera and dash-camera video;
- the testing sequence;
- whether HGN was mentioned and how it was used;
- chemical-test or refusal paperwork;
- medical conditions affecting balance, eyes, speech, or movement;
- witness information;
- and the court where the case is pending.
For broader arrest guidance, see what to do if you're arrested in Mississippi. For the general DUI timeline, see DUI in Mississippi.
Mississippi Field Sobriety Test FAQ
Are field sobriety tests the same as the breath test?
No. Roadside field sobriety exercises are different from the evidentiary chemical test governed by Mississippi's implied-consent framework. Breath, blood, and urine testing raise different issues from walk-and-turn, one-leg stand, and HGN.
Does failing field sobriety tests mean I am guilty?
No. Field sobriety evidence may be part of the State's case, but it is not automatically conclusive. The court or jury may consider the conditions, instructions, video, medical limitations, and the rest of the evidence.
Does passing field sobriety tests mean the case gets dismissed?
Not automatically. The State may rely on other evidence, including driving behavior, officer observations, statements, refusal evidence, or chemical-test results.
What is HGN?
HGN is an eye-movement test. Mississippi treats HGN differently from ordinary balance-and-coordination evidence. Under Young v. City of Brookhaven, HGN is not admissible before the jury to prove intoxication or impairment, though it may be used for probable-cause issues.
Can medical conditions matter?
Yes. Medical, physical, balance, eye, neurological, anxiety, fatigue, and medication issues may affect how field sobriety evidence should be viewed. They do not automatically defeat the charge, but they can matter.
Get a Consultation
Sheppard Law Firm represents people facing DUI and criminal charges in Mississippi, including cases involving field sobriety evidence, HGN, chemical testing, refusal, and court-specific DUI procedure. Call 601-688-4110 or start a criminal defense review before you enter a plea or miss a deadline.