Breath-Alcohol Testing State of the Art
Information courtesy of Lawrence Taylor - DUIblog
All states now have two drunk driving laws: (1) driving under the influence of alcohol (aka "DUI", with local variations, such as "driving while intoxicated" or "DWI"), and (2) the so-called per se law of driving with .08% or higher blood-alcohol concentration (BAC). Most of those arrested will be charged and prosecuted for both offenses.
The breath machines (commonly -- and inaccurately -- referred to as "Breathalyzers") used to obtain the BAC are, obviously, critical to the drunk driving case. As for the per se offense, the only evidence of the crime is the machine: if the thing says .08% or higher and the jury believes it, the defendant is guilty. And even as to the DUI charge, the readings will be considered presumptive: if the BAC is .08% or higher, the jury will be instructed by the judge that the defendant is presumed guilty -- and he must be found guilty unless he can prove his innocence (I've discussed this in "Whatever Happened to the Presumption of Innocence?").
These machines are all-important: they determine guilt or innocence. But their manufacturers continue to assure us that they are "state of the art". So how accurate are they? Not very.