Anne ImObersteg has qualified in court as an expert in breath testing technology, breath testing procedures, and the maintenance and operation of all the major breath testing machines. Ms. ImObersteg ownes several machines, including the Intoximeter's AlcoSensor III, IV, and RBT IV, and CMI's Intoxilyzers 4011A, 4011AS, 5000 (64, 66, 68 series) and the 5000EN.

Roadside breath testing devices are typically fuel cell devices, since the technology allows the fuel cell to be small, and the instruments to be handheld. A fuel cell is an electrochemical cell, which continuously transforms the chemical energy of a fuel and an oxidating material, such as ethanol, into electrical energy. Breath flows over the fuel cell, interacts with an electrolyte, such as sulfuric acid, and electrons are extracted. The quantity of electrons released from the fuel cell is measured and converted to a blood alcohol concentration.

Most evidential breath testing instruments use infrared technology to determine the amount of alcohol in the breath. Molecules absorb energy at specific areas in the IR spectrum. When IR energy is passed though a chamber filled with ethanol molecules, the molecules will absorb energy at specific wavelengths. Ethanol molecules absorb at the 3.30um to 3.60um range and the 9.00um to 10.00um range. When the energy is absorbed by the ethanol molecule, an IR detector will detect the drop in IR energy and convert this change to a reading via a mathematical formula known as Beer's law. Some machines, such as the Draeger 7110 MKIII utilizes both an IR and a fuel cell.

Below are some features of the major machines in use today: