IID stands for Ignition Interlock Device It's made up of 2 parts, the 1st part is the breathalyzer that you hold and breath into, the breathalyzer is connected to the engine of your car with a cord, if your BAC, Breath Alcohol Concentration level is below the limit set by your state then the vehicle will start, if the BAC above the limit set by your state then the engine of your vehicle will not start. This will be connected to your engine by law after DUI arrest, see the law at the DUI arrest page

DUI lawyer, you have days. You may be ordered to install IID device on your engine.