Breath Testing Instruments

Breath Test Devices

Evidential Breath Testing. An individual suspected of DUI is often required to submit to evidential breath testing administered by law enforcement officers. Evidential breath testing devices produce printouts that are generally admissible as evidence in a court of law. Evidential Breath Testing devices on the National Highway Traffic and Safety Administration’s conforming products list (CPL) are the only devices which may be used to conduct alcohol confirmation tests under 49 CFR Part 40.

At a minimum, NHTSA requires that all evidential breath test instruments:

  • Provides a printed triplicate result (or three consecutive identical copies of a result) of each breath test;
  • Assigns a unique number to each completed test, which the BAT and employee can read before each test and which is printed on each copy of the result;
  • Prints, on each copy of the result, the manufacturer's name for the device, its serial number, and the time of the test;
  • Distinguishes alcohol from acetone at the 0.02 alcohol concentration level;
  • Tests an air blank; and
  • Performs an external calibration check.

There are a multitude of instruments currently in use throughout the United States. Some states even employ multiple instruments depending on jurisdiction. While the science behind these instruments is generally the same, each machine has unique functions, capabilities and limitations.

Below you will find pages dedicated to some of the most common instruments currently being used by law enforcement nationwide. For more information about specific breath test instruments currently in use, contact a State Delegate today or visit our Virtual Forensic Library.

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FROM OUR BLOG

How DUI Case Outcomes Can Affect Firearm Rights and Explosives Privileges

07/30/2026

By Christine B. Vazquez FL State Delegate, NCDD Collateral Consequences Task Force Katz & Phillips, P.A., Orlando, FL As DUI defense attorneys, we often evaluate collateral consequences such as license suspensions, employment consequences, and immigration concerns. That same analysis should extend to firearm and explosives restrictions, particularly when the client is charged with a felony-level DUI, owns firearms, holds a concealed-carry license, or works...

The Disconnect Defense: Defeating a Breath Test Twice the Legal Limit

06/29/2026

By Hunter TzovarrasChair, NCDD Trial Advocacy Task ForceThe Law Office of Hunter J. Tzovarras, Bangor, Maine With assistance from Myranda G. SandbergMember, NCDDNero DUI Defense, S.C., Eau Claire, Wisconsin "It doesn't matter what number the machine prints out if the video shows you walk, talk, and act sober." That is what I tell clients who are sure a high breath test means...

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