The Web's Premiere Guide To Handling A California DUI.

DUI Breath Test Machines

Most citizens arrested for DUI in California opt for a breath alcohol test. A series of different DUI breath test machines are used by the various Southern California counties. An experienced California DUI defense attorney can challenge the reliability of any of the alcohol breath testing devices below.

Each of the DUI breath test machines attempts to measure the concentration of alcohol in the deep lung region called the "alveoli." The concentration of alcohol in the "alveolar air" is thought to correspond to the concentration of alcohol in the blood. In theory, then, a person's breath alcohol level will roughly approximate his/her blood alcohol level.

The DUI breath test devices employ one or both of two technologies: (1) infrared spectroscopy or (2) fuel cell (electrochemical oxidation). Unfortunately, both of these DUI breath testing methods is deeply flawed and plagued with problems that can lead to the wrongful prosecution (and conviction) of innocent DUI defendants.

  • BAC DataMaster
    The BAC DataMaster is used for all Los Angeles County DUI cases (excluding those in the cities of Los Angeles and Long Beach)

  • Intox EC/IR
    The Intox EC/IR is used for DUI cases in the City of Los Angeles

  • Draeger Alcotest 7110
    The Draeger Alcotest 7110 is used for San Bernardino and Riverside County DUI cases. More information about the Draeger Alcotest 7110

  • Draeger Alcotest 7410
    The Draeger Alcotest 7410 is used for Orange County DUI cases

  • Intoxilyzer 5000
    The Intoxilyzer 5000 is used for Long Beach DUI cases

  • Intoxilyzer 8000
    The Intoxilyzer 8000 is used for San Diego DUI cases

DUI Breath Testing & Infrared Spectroscopy

Most DUI breath test devices today use "infrared spectroscopy" as their means of measuring breath alcohol levels. The underlying idea is that all chemicals (including alcohol) absorb infrared radiation at specific wavelengths. Ethyl alcohol absorbs strongly in the infrared wavelength range of 3.3 to 3.5 microns, and also at 9.5 microns.

The DUI breath machines using infrared spectroscopy shoot infrared energy through a sample chamber. The suspected drunk driver blows into the sample chamber. The amount of infrared energy lost due to absorption by ethyl alcohol molecules is thought to be proportionate to the DUI suspect's breath alcohol concentration.

DUI Breath Testing & Fuel Cell Devices (Electrochemical Oxidation)

A fuel cell is a machine intended to constantly convert fuel and an oxidant into a direct current. With DUI breath test machines, alcohol (in the breath sample blown into the machine) is used as the fuel and oxygen from the atmosphere as the oxidant.

Through a process called electrochemical oxidation, the fuel cell converts alcohol to acetic acid. This generates two electrons for each alcohol molecule. These electrons spark an electric current that is thought to measure the amount of alcohol in the DUI suspect's breath sample.