All breathalyzers sold to consumers in the US must be certified by the FDA. The FDA certification process assures the user that a breathalyzer is “substantially equivalent” to other breathalyzers on the market, and that it does what it claims to do. There is also an accuracy standard that breathalyzers have to pass as part of the process. Most breathalyzers on the market are not FDA certified, despite the FDA’s regulations, but at present the FDA does not have the power to stop their sale.
The breathalyzers that are used in a professional environment, such as those used by the police, must be approved by the Department of Transportation (DOT). Some of these are approved as breath alcohol screening devices, which means that their purpose is not so much to accurately measure the level of alcohol, but to simply determine whether there is alcohol present in the breath sample or not. Some breathalyzers that are sold to consumers are approved by the DOT as breath alcohol screening devices, but DOT approval does not substitute for FDA certification, nor does it mean that these breathalyzers are more accurate than those that have FDA certification.