The New York City Police Department uses for the most part, the Intoxilizer 5000 to conduct breathelyzer tests of people arrested for DUI in the Queens. This usually starts with a police officer claiming that he smelled alcohol on a driver’s breath. The machines used in NYC are notoriulsy malfunctionining. One specific machine has been taken in and out of service several times. The whole premise behind the breathalyzer is flawed.
So why do the police use these machines? Because its easy and cheap! The machine prints out a neat number for the courts to prosecute people on. These machines drive Queens DWI lawyers crazy. I have seen countless cases where the driver is dead sober and the machine says that he is drunk. Additionally, the Blood Alcohol Level of .08 is completely arbitrary. Its just a number politicians could agree on when they drafted the legislation.
A few years ago the BAC was .10 but then groups like MADD lobbied and had it reduced to .08. So being judged to be drunk simply depends on politics.