When a New Hampshire police officer stops a driver on suspicion of drunk driving, the officer may require the driver to take a preliminary breath test to estimate the driver’s blood alcohol concentration (BAC). Many different manufacturers make breath testing machines, but New Hampshire law requires breath test machines to meet certain standards before they can be used by state or local police.
For instance, New Hampshire preliminary breath test machines must be among those “identified on the National Highway Traffic Safety Administration’s “Conforming Products List” of evidential breath measurement device.” The machine must also be able to correctly analyze a test sample and must pass all other regulations and testing, which are performed by the state police laboratory.
Before a breath test machine can be used on New Hampshire drivers, the police laboratory examines and calibrates the machine to determine whether it meets the state’s legal standards. In order to pass, a preliminary breath test machine must be able to correctly identify the amount of alcohol in several different samples. The samples are pre-arranged so that the specific amount of alcohol in them is already known, and the machine is expected to get the number right. If it cannot, it cannot be used by officers on patrol. The machines are also evaluated for ease of use, performance in a wide range of outdoor temperatures, and how much other factors, like the presence of electromagnetic radiation, affect their function.