Breath Tests and Field Sobriety Tests in NC DWI Cases

How DWI Evidence Is Gathered in the Outer Banks

Most North Carolina DWI cases rest on three kinds of evidence: what the officer saw while you were driving, field sobriety tests at the roadside, and a chemical test of your breath or blood. Each one has rules, and each one can be reviewed.

On the Outer Banks, roadside tests are often given on the shoulder of US 158 or NC 12, at night, in wind, on uneven ground or sand, and in whatever shoes a visitor was wearing. Those conditions matter when the results are evaluated.

Daniel Donahue is a Board Certified Specialist in State and Federal Criminal Law, certified by the North Carolina State Bar Board of Legal Specialization. He is the only board-certified criminal law specialist based in Dare County. He holds NHTSA certification in standardized field sobriety testing and has completed DWI training at Harvard Law School, and he handles DWI cases in Dare and Currituck County courts.

Charged with DWI after field sobriety or breath tests in Dare or Currituck County? Call or text Donahue Defense at 252-715-5785.

Standardized Field Sobriety Tests

The National Highway Traffic Safety Administration (NHTSA) trains officers on three standardized field sobriety tests. Each is supposed to be given the same way every time, with specific instructions and specific clues the officer scores.

• Horizontal gaze nystagmus (HGN): the officer watches your eyes as they follow a stimulus, looking for involuntary jerking.
• Walk-and-turn: nine heel-to-toe steps along a line, a turn, and nine steps back, while following instructions.
• One-leg stand: standing on one foot while counting aloud for about 30 seconds.

Other roadside tasks, such as reciting the alphabet or counting backward, are not part of the standardized battery. Footwear, surface, weather, lighting, injuries, and medical conditions can all affect how a person performs.

Roadside Portable Breath Tests

An officer may ask you to blow into a portable alcohol screening device at the roadside under N.C.G.S. Section 20-16.3. In court, only whether the result was positive or negative can be used, not the number, and only to decide whether the officer had grounds for an arrest. It cannot prove a particular alcohol concentration.

The Breath Test at the Station

North Carolina uses the Intoximeter EC/IR II for evidentiary breath tests. Under N.C.G.S. Section 20-139.1:

• The test must follow the rules of the NC Department of Health and Human Services.
• The person giving the test must hold a current DHHS permit for that type of instrument.
• At least two sequential breath samples are required.
• The results are admissible only if two consecutive samples are within 0.02 of each other, and only the lower result can be used to prove your alcohol concentration.

Your Rights Before a Chemical Test

Before a breath or blood test, the officer must tell you your rights under N.C.G.S. Section 20-16.2, both orally and in writing. They include:

• You can refuse any test, but refusal brings a one-year revocation and can lead to a longer one.
• The results, or the fact that you refused, can be used as evidence at trial.
• A result of 0.08 or more, or a refusal, brings an immediate revocation of at least 30 days.
• After you are released, you may seek your own test in addition to the officer’s test.
• You may call an attorney and select a witness to view the testing, but the test will not be delayed more than 30 minutes for that purpose.

Learn more about refusal and license revocation.

Blood Tests

Blood is often drawn when drugs are suspected or when a breath test is not possible. A blood sample can be taken with your consent or with a search warrant. The statute allows a blood draw without a court order only in limited circumstances, and constitutional limits apply. Blood results depend on how the sample was drawn, stored, and analyzed, and on the lab records that document each step.

How We Review the Evidence

• Dash camera and body camera video of the stop and the roadside tests
• Whether the field sobriety tests were given and scored according to NHTSA standards
• The breath instrument records, the operator’s permit, and whether the required procedures were followed
• Blood draw, chain of custody, and lab records
• Whether you were properly advised of your rights before any chemical test

Breath and Field Sobriety Test FAQs

Can I refuse the roadside portable breath test?

Refusing the roadside screening test is not the same as refusing the chemical test at the station. But the refusal can be used in deciding whether the officer had grounds to arrest you.

What if my two breath samples were far apart?

The statute requires two consecutive samples within 0.02 of each other before the results can be used. Whether a test met that standard is something we check in every breath test case.

Does a 0.08 result mean I will be convicted?

No. A result of 0.08 or more is one way to prove DWI, but the State still has to prove its case, including that the test was given according to the rules.

Are field sobriety tests scientific?

The three standardized tests were developed through NHTSA research, and officers are trained to give them a specific way. How closely an officer followed that training is a central question in reviewing the results.

Talk to an Outer Banks DWI Lawyer

If you were charged with DWI in Dare or Currituck County, call or text 252-715-5785. We will review how the tests were given and explain what the evidence means for your case. Visiting from out of state? See out-of-state DWI. Se habla español.

Please do not include confidential or sensitive information in a contact form, text message, or voicemail.

This page is general information about North Carolina law, not legal advice for your situation.