This report presents a literature review of driving while intoxicated or impaired screening instruments and procedures for assessing drunk drivers. It also provides a list of instruments and procedures that state court systems report they currently utilize. The review aims to identify studies that look at whether screening procedures in and of themselves are effective deterrents for future drunk driving. The report also presents an in-depth evaluation of instruments used to screen DWI drivers and defines the depth and breadth of the field's knowledge of their effectiveness and practical considerations for when and how they are used.