Driving While Intoxicated is the offense of operating a motor vehicle while under the influence of alcohol or drugs. State law controls whether operating includes actual driving of the car or merely sitting in the car and the level of intoxication needed in order to be found in violation of the law. Some statutes refer to driving under the influence (DUI) or driving while impaired (DWI) that does not require intoxication. DUI and DWI lawyers represent people who have been arrested and charged with driving under the influence of alcohol or drugs. DUI and DWI attorneys defend clients at each stage of a DUI or DWI case -- from arrest to an appeal after conviction. A DUI and DWI attorney may challenge aspects of a DUI or DWI arrest or conviction, including breathalyzer and chemical testing procedures.