How Breathalyzers Work
An excellent explanation of the theory and operation of breath testing devices for the layman.
Introduction to Forensic Toxicology
Good overview of the science of analyzing poisons — including blood-alcohol analysis.
Breath Testing Machines
Very basic discussion of the most common methods of breath analysis, from the National Highway Traffic Administration.
The homepage of the manufacturer of one of the most commonly used breath machines.
Drunk Driving Guide Sections
The Breath Machine