An ignition interlock is a device attached to the vehicles mechanical system which prevents the car from being started without the driver providing a sample of breath devoid of any alcohol. The device will monitor and report failed attempts to start the vehicle. Defendants convicted of driving under the influence charges must have them installed on the vehicle they own as a matter of state law. Also, in certain circumstances, Leesburg and Loudoun judges often require the installation of such devices as a condition of granting restricted driving privileges even when a driving under the influence charges charge is reduced to a lesser charge.