PBT Portable Breath Test Calibration in North Carolina

North Carolina regulates portable breath tests (PBTs), sometimes referred to as the “breathalyzer,” through specific administrative rules and statutory provisions. Law enforcement officers regularly rely on alcohol screening devices to assess whether a driver has consumed alcohol and may be part of the “arrest decision” related to probable cause. To better ensure reliable readings, the Department of Health and Human Services (DHHS) requires that approved devices be calibrated and verified for accuracy on a regular basis. Deviation from the rules is problematic at best and can, in some circumstances, raise doubt about whether a reported BAC reflects the true breath alcohol content.

This article explains how PBTs fit into North Carolina’s regulatory framework and why calibration rules are important. It references 10A NCAC 41B .0503 and related guidelines for monthly checks, breath simulator solutions, and ethanol gas canisters. If you have questions about calibration or how a screening test may apply to your legal matter, give us a call or text the Powers Law Firm at 704-342-4357. You may also email Bill Powers directly at Bill@CarolinaAttorneys.com.

Below is a synopsis of the sections covered in this article. Each entry links to a segment that discusses calibration and how law enforcement officers administer roadside breath tests in North Carolina.

North Carolina’s PBT and Breathalyzer Framework
Device Approval and Regulatory Authority
Calibration Basics: 30-Day Checks and Simulator Solutions
Ethanol Gas Canisters and Expiration Dates
Logs and Recordkeeping Procedures
Operational Instructions for Roadside Use
Statutory Overview: G.S. 20-16.3 and Relevant Law
Reliability Concerns and Potential Disputes
Practical Considerations for Agencies and Drivers
Your DUI Defense Lawyers: Powers Law Firm

1. North Carolina’s PBT and Breathalyzer Framework

North Carolina’s system for breath testing involves protocols established by the Forensic Tests for Alcohol Branch, operating under DHHS, and as set forth in the North Carolina Administrative Code. The Forensic Tests for Alcohol branch evaluates devices that measure breath alcohol content, determining whether they meet the minimum standards for reliability. Once approved, devices appear on a published list, and operators are directed to follow instructions regarding calibration, maintenance, and proper usage.

Devices such as the Alco-Sensor or other portable “breathalyzers” do not serve as the final evidentiary test in a Driving While Impaired (DWI) case. Instead, they act as an on-the-spot screening tool. The officer may rely on the reading to decide if there are grounds for further testing. That final evidentiary step may involve a more sophisticated and reliable machine—like the Intox EC/IR II—at a law enforcement facility, intake facility or local jail.

Still, a roadside device can influence an officer’s decision to arrest, and evidence of a positive (or negative) reading for alcohol may become relevant on the issue of probable cause to arrest. North Carolina’s regulations emphasize calibration and recordkeeping. If calibration rules are not met, a defense attorney might question whether the device is reliable, accurate, and/or other admissible as evidence in a trial or motion to suppress.

2. Device Approval and Regulatory Authority

The makes and models of breath screening devices that DHHS approves are set forth in the North Carolina Administrative Code—particularly 10A NCAC 41B .0503—identifies various instruments, such as:

Alco-Sensor series (manufactured by Intoximeters, Inc. and most commonly used PBT in North Carolina)
S-D2 and S-D5 (manufactured by CMI, Inc.)
Lifeloc FC10 (manufactured by Lifeloc Technologies, Inc.)
Alcovisor Mercury (manufactured by PAS International)

These devices undergo an evaluation to confirm they meet requirements for stability, cost, ease of operation, and consistent results. The Forensic Tests for Alcohol Branch:

Evaluates and approves devices for use.
Sets guidelines for how agencies should maintain logs and verify calibration.
Provides training and documentation on how to run tests properly.

However, the Branch does not necessarily routinely audit every agency’s logs or physically check that each device meets the 30-day calibration deadline. Agencies themselves bear responsibility for compliance. If problems emerge—such as in a contested DWI case—records may come under scrutiny, and the Branch could be consulted or might review data in response to questions or investigations.

Post Mortem BAC – Blood Alcohol Concentration

Furthermore, approval of a particular make and model PBT by the FTAB alone does not guarantee an error-free process. The individual device at issue must remain in the same condition it was when tested as part of the approval process by the Forensic Tests for Alcohol Branch. That includes following a set regimen for calibration checks and solution changes. If the operator deviates from those steps, the reading may lose credibility.

As such, law enforcement agencies are charged with the responsibility of maintaining records and running monthly checks, but the bulk of compliance responsibility rests with those agencies rather than the Branch.

3. Calibration Basics: 30-Day Checks and Simulator Solutions

One core requirement involves recalibrating or at least verifying the accuracy of the device every 30 days. The operator uses a known alcohol concentration to confirm the reading matches expectations. This helps ensure the sensor has not drifted. North Carolina references the concept of an “alcoholic breath simulator,” which produces a vapor containing ethanol.

Verifying Accuracy means testing a device against a known standard to see if the reported result matches the expected number. If the device’s reading is consistent with that standard, no further adjustment is needed. For example, an operator might run an “alcoholic breath simulator” check and compare the displayed BAC to the known concentration in the simulator solution.

Recalibrating goes a step further by adjusting the device if the reading is out of range. When recalibration happens, the device’s internal settings or sensor align with the known standard. If the device fails accuracy checks, the operator or a trained technician recalibrates it to bring it back to acceptable limits.

In short, verifying checks whether the measurement is on target, while recalibrating corrects any discrepancy so the device’s readings align with the true value.

Replacing Simulator Solution: The solution in the simulator must be changed every 30 days or after 25 calibration tests, whichever comes first. This keeps ethanol purity at a more predictable level. An operator who attempts to stretch the solution beyond its limits may receive inconsistent results.
Temperature Control: The simulator requires heating to a specific temperature so that ethanol vaporizes at the intended rate. A drop in temperature or a device malfunction could cause a false reading.

Once the operator completes a successful check, the device is presumed to measure a real breath sample with similar accuracy. If the device fails the check, it should be taken out of service or corrected. An out-of-service device used on the roadway might lead to questions about whether the driver’s reading was inflated or understated.

The Art of Plea Negotiations

4. Ethanol Gas Canisters and Expiration Dates

Instead of an alcoholic breath simulator, operators may rely on ethanol gas canisters. These canisters contain pressurized ethanol vapor at a known concentration at a given altitude (sea level):

Expiration Date: Each canister has a label indicating when it is no longer valid. Once that date passes, the canister’s ethanol concentration may degrade.
Log Entries: The operator notes each time the canister is used for a calibration check, including the reading and the date. This practice helps the law enforcement agency prove it performed calibration within the allowed timeframe.

If a canister expires but remains in circulation, the device’s calibration check may yield questionable data. Defendants who face DWI charges might ask to review the test PBT logs and records to see if the canister had expired when the officer ran the verification. That detail can affect whether a court believes the PBT reading was consistent with the relevant DUI laws and administrative code provisions.

5. Logs and Recordkeeping Procedures

Paragraph (e) of 10A NCAC 41B .0503 directs agencies to record calibration verifications on log forms designed by the Forensic Tests for Alcohol Branch within the North Carolina Department of Health and Human Services. Agencies maintain these logs according to their own retention policies. A typical entry includes:

Date and time of the check
Device serial number
Simulator solution lot number or canister number
Outcome of the verification (did the device align with the expected reading?)
Name or initials of the operator

The Administrative Code does not establish a single statewide retention period. Instead, each user agency decides how long to keep these records. When logs are incomplete or missing, a defense attorney may question the reliability of a reported breath test result. The state authorizes these devices on the premise that agencies will follow calibration procedures, so any gap in logs can reduce confidence in the measurement.

Are Patdown Searches Legal?

6. Operational Instructions for Roadside Use

Roadside Screening Test Steps under 10A NCAC 41B .0502

The Administrative Code describes how an officer administers a roadside breath screening test. While agencies may also refer to manufacturer guidelines, section .0502 lays out specific steps for removing substances from the mouth and retesting if a high initial reading appears. Below are highlights of what the regulation covers:

Mouth Check
The officer is instructed to ensure the driver has removed food, drink, tobacco products, gum, or other objects from the mouth. Items retained in the mouth can trap or mask alcohol, affecting the reading.
Wait Period After a High Reading
If an initial screening shows an alcohol concentration of 0.08 or higher, section .0502 directs the officer to wait about five minutes and then administer another test. If the second reading differs from the first by more than 0.02, the officer may disregard the first result.
Multiple Tests
The regulation allows the officer to request one or more extra roadside tests. Each result can help the officer decide whether to pursue a more detailed, evidentiary breath test under implied-consent laws.

These steps address possible issues like residual mouth alcohol or a momentary spike in the reading. If the officer neglects to remove items from the driver’s mouth, fails to wait before retesting, or does not follow the guidelines for repeated tests, the reliability of the screening result may come under scrutiny. In a disputed DWI matter, defense counsel may review how the screening was carried out and whether the officer followed 10A NCAC 41B .0502 precisely.

What is a Substance Abuse Assessment & What Does it Involve?

7. Statutory Overview: G.S. 20-16.3 and Relevant Law

North Carolina General Statute 20-16.3 explains when a law enforcement officer may request a roadside breath screening test. The officer must have reasonable grounds to suspect the driver has consumed alcohol and either committed a traffic offense or been involved in a crash. The officer must also use a device approved by the Department of Health and Human Services and follow the relevant operating rules.

Requesting a roadside screening test under G.S. 20-16.3 is not an arrest. It is a preliminary procedure used to decide whether there is enough cause to conduct a formal implied-consent test under G.S. 20-16.2. While a positive or negative result from the screening test can influence the officer’s decision, it does not itself determine guilt or serve as final proof of a driver’s exact BAC at trial.

Subsection (d) of G.S. 20-16.3 notes that the specific numeric reading from the device is generally not introduced in court to prove an exact alcohol concentration. However, the officer can testify to whether the screening indicated the presence or absence of alcohol, which may support probable cause.

Critical Analysis of Standardized Field Sobriety Tests

8. Reliability Concerns and Potential Disputes

Although PBT devices have a relatively straightforward design, multiple factors can prompt disputes about a reading:

Calibration Lapse: If no log entry shows a device check for more than 30 days, the result could be viewed as unreliable.
Expired Canister: A canister used past its expiration date might skew the test. The code directs operators not to rely on gas canisters that have exceeded the labeled date.
Simulator Solution Issues: If the solution was changed late or exceeded the 25-test limit, the operator might not realize the device’s sensor is off.
Mouth Residual: If the driver consumed a beverage close to the time of testing, leftover alcohol in the mouth can produce an elevated reading that does not match the driver’s bloodstream alcohol level.

These points do not always invalidate a PBT, but they may create questions about how the officer reached a decision to arrest. A defense attorney may review each detail to see if the reported reading reflects actual impairment or if it stems from poor upkeep or improper testing methods.

BIG CHANGES to North Carolina’s DUI Limited Driving Privilege Laws

9. Practical Considerations for Agencies and Drivers

Agencies that use PBTs should plan for monthly calibration checks, fresh simulator solutions or valid canisters, and prompt log entries. They should also train operators to follow mouth-check procedures and potential wait periods after a high reading. In North Carolina, an officer who uses a PBT is not required to be a Licensed Chemical Analyst.

Under North Carolina law, a roadside test (PBT) is not an implied-consent test, so refusing it does not lead to an automatic license revocation. However, G.S. 20-16.3 states that an officer “shall” consider a refusal when forming an opinion about probable cause. Officers typically record refusals in their investigation reports, and that detail may influence the decision on whether to proceed with a formal implied-consent test.

A defense attorney who suspects an officer used an expired canister or failed to replace the simulator solution on time may wish to review the calibration logs. These records confirm whether the device was verified within 30 days and whether the required solution was changed as mandated. If the logs are incomplete or missing, the PBT reading may carry less weight if challenged later.

How the Police Conduct a Criminal Investigation BEFORE ARREST

10. Your DUI Defense Lawyers: Powers Law Firm

Officers in North Carolina are expected to follow calibration guidelines for portable breath tests (PBTs) and breathalyzers, including monthly checks, proper simulator solution changes, and valid gas canisters. If these steps are not documented or logs are incomplete, the resulting BAC number may not reflect real conditions. A defense attorney may want to review those logs, verify whether the calibration schedule was met, and assess if the officer followed the procedures outlined in the Administrative Code and state statutes.

If you have questions about calibration requirements or want to discuss how breathalyzer readings could influence a legal matter, consider reaching out to the Powers Law Firm. You can call or text 704-342-4357, or email Bill Powers at Bill@CarolinaAttorneys.com.

Table of Contents