As of January 1, 2009, individuals arrested and/or convicted of DUI will have the opportunity to apply for a Ignition Interlock Driver's License instead of an Occupational License (which previously only followed a period of suspension).
RCW 46.20.385 governs all individuals who have been convicted of DUI or Physical Control, or who have had their license administratively suspended by the Department of Licensing.
The primary difference between the current and previous law is that the Ignition Interlock License does not have limitations on time and location for the driver. So long as they have the Ignition Interlock properly installed in the vehicle they can drive it.
http://www.dol.wa.gov/forms/500023.pdf
