Rules for Breath Tests in DWI Cases

The easiest way for the State to prove impairment in a prosecution for impaired driving is by introducing the results of a test of the defendant’s breath. Such test results are admissible without the foundation that would otherwise be required for this kind of scientific evidence so long as the testing was carried out in accordance with statutory and administrative rules governing implied consent testing. G.S. 20-139.1(b). Because the rule allowing breath test results to be introduced into evidence is relied upon so often, I thought it might be helpful to review the admissibility rule and the requirements for such tests.

There are two admissibility rules set forth in G.S. 20-139.1. The first applies to chemical analyses generally. It provides that in an implied consent case, a person’s alcohol concentration or the presence of any other impairing substance in the person’s body as shown by a chemical analysis is admissible in evidence. G.S. 20-139.1(a). A chemical analysis is a test of a person’s breath, blood or other bodily fluid or substance to determine the person’s alcohol concentration or presence of an impairing substance carried out in accordance with G.S. 20-139.1. G.S. 20-4.01(3a).

The second rule applies only to breath tests. It provides that a chemical analysis of the breath administered pursuant to the implied-consent law is admissible in any court or administrative hearing or proceeding if (1) it is performed in accordance with the rules of the Department of Health and Human Services, and (2) the person performing the analysis had, at the time of the analysis, a current permit issued by the Department of Health and Human Services authorizing the person to perform a test of the breath using the type of instrument employed.

DHHS rules. The Department of Health and Human Services has adopted numerous rules governing implied consent testing, which are codified in Subchapter 41B of Title 10A of the North Carolina Administrative Code.

Before it was amended in 2006, G.S. 20-139.1 specifically authorized DHHS to adopt rules “approving satisfactory methods or techniques for performing chemical analyses,” and directed DHHS to adopt regulations requiring “the testing of at least duplicate sequential breath samples,” specifying the “minimum observation period before collection of the first breath sample and the time requirements as to collection of second and subsequent samples,” and specifying that the test results could only be used to prove a person’s alcohol concentration if the readings were from consecutively administered tests and did not differ by more than 0.02. G.S. 20-139.1(2005).

The current version of G.S. 20-139.1 refers to DHHS rules but does not specifically authorize their promulgation. In addition, G.S. 20-139.1 no longer requires that DHHS specify the minimum observation period, though DHHS still has a rule setting forth that requirement. In any event, under the current version of the regulations, there are three main requirements for breath tests.

Observation period. The chemical analyst must observe the person to be tested to determine that the person has not ingested alcohol or other fluids, regurgitated, vomited, eaten, or smoked in the fifteen minutes immediately prior to the collection of a breath specimen. The chemical analyst may observe while he or she is setting up the breath testing instrument. 10A NCAC 41B .0101(6), .0322.

Preventative maintenance. The breath testing instrument currently in use statewide is the Intoximeter EC/IR II. DHHS regulations require that those machines undergo preventative maintenance every 4 months. 10 NCAC 41B .0323. Unlike earlier breath testing instruments that used an water-alcohol solution to check accuracy, the Intoximeter uses an ethanol gas canister for this purpose. The gas canister must be changed before its expiration date. 10 NCAC 41B .0323. In determining whether preventative maintenance has been performed, courts are required to take judicial notice of the preventative maintenance records of DHHS. G.S. 20-139.1(b2).

If the defendant objects to the admission of breath test results and demonstrates that preventative maintenance has not been timely performed, the results are not admissible. G.S. 20-139.1(b2). But see State v. Simmons, 205 N.C. App. 509, 527 (2010) (rejecting defendant’s argument that breath test results were inadmissible due to lapse in preventative maintenance before he was tested since preventative maintenance was performed 23 days before defendant’s test).

Sequential breath samples. G.S. 20-139.1(b3) requires that the methods governing the administration of breath tests require the testing of “at least duplicate sequential breath samples.” The provision further provides that the results of the chemical analysis of all breath samples is admissible if the test results from any two consecutively collected breath samples do not differ by more than .02. G.S. 20-139.1(b3). Breath samples separated by an intervening insufficient sample may satisfy this requirement. See State v. Cathcart, 227 N.C. App. 347, 351–52 (2013) (deeming breath test results obtained eleven minutes apart that were separated by an intervening insufficient sample to be sequential and thus admissible).

G.S. 20-139.1(b3) states that only the lower of the two test results of the consecutively administered tests may be used to prove a particular alcohol concentration. A person’s refusal to give the second or subsequent breath sample makes the result of the first sample or the sample providing the lowest alcohol concentration if more than one breath sample is provided admissible.  Thus, if a person’s breath test results were .11 and .08, followed by a refusal, the .08 result would be admissible.

The operational procedures for conducting a breath test on the Intoximeter EC/IR II are set out in 10A NCAC 41B .0322.

That regulation provides as follows:



Permit requirement. Recall that the second admissibility requirement in G.S. 20-139.1(b) is that the person performing the analysis have a current permit issued by DHHS authorizing the person to perform a breath test on the instrument the person used. G.S. 20-139.1(b)(2). The issuance of such a permit renders the person a chemical analyst under G.S. 20-4.01(3b). The list of permitted analysts is available here, and the court is required to take judicial notice of the list for purposes of establishing the permit requirement. G.S. 20-139.1(b).

Implied consent testing rules. A threshold issue in any case involving the admission of chemical analysis results is whether the testing was carried out in accordance with the general requirements for implied consent testing set forth in G.S. 20-16.2. Indeed, G.S. 20-139.1(b) refers to chemical analyses of breath that are “administered pursuant to the implied-consent law.” G.S. 20-16.2 requires, among other things, that a law enforcement officer have probable cause to believe that the defendant committed an implied consent offense, that the defendant be charged with the offense, that the defendant be taken before a chemical analyst with a DHHS permit, and that the chemical analyst advise the person orally and in writing of his or her implied consent rights. If these procedures are not followed or the rights promised are not afforded, the test results may be suppressed, as discussed in several earlier posts (here, here, here, here, and here). See State v. Shadding, 17 N.C. App. 279 (1973).

Why are breath test results so significant? The impairment element of the crime of driving while impaired may be proved by demonstrating that the defendant drove after having consumed sufficient alcohol that he or she had, at any relevant time after the driving, an alcohol concentration of 0.08 or more. G.S. 20-138.1(a)(2). Because the State is not also required to prove that the defendant was appreciably impaired or that he or she drove in an unsafe manner, see State v. Arrington, 215 N.C. App. 161 (2011), the results of a breath test may be all the proof the State needs to convince the finder of fact about that particular element.

3 thoughts on “Rules for Breath Tests in DWI Cases”

  1. Shea, please refer to NCAC 10A 41B; .0101#2 Breath Testing rule they are breath testing INSTRUMENTS and not machines .Thanks

  2. So, statutory and administrative rules obviate the need for a foundation for this kind of scientific evidence. Is there a separation of powers issue here?

    Imagine if a foundation were required. Could the administrative rules pass the scrutiny of Rule 702 and McGrady/Daubert? No. The reason is simple. The rules are not scientific. They are fiat. Most problematic is that the rules admit of no uncertainty in measurement. Results are “deemed accurate.” This is in spite of a fundamental rule of science: All scientific measurements have some amount of uncertainty.

    By contrast, the procedure for measuring the amount of alcohol in blood would pass scrutiny. The reason is simple. The procedure is scientific. Noteworthy in this regard, alcohol results are reported along with accompanying uncertainty.


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