The guide first explains the language of Section 21-902 of the Maryland Transportation Article which contains relevant offenses that the prosecutor will have to prove to obtain a conviction and jurisdiction over DWI cases. It then focuses on methods used to apprehend DWI offenders -checkpoints, police observations, roadside sobriety tests, and the prearrest breath test -- and discusses the applicability of Miranda warnings, search and seizure laws, and right to counsel to DWI offenders. Rules providing the statutory authority for administering chemical tests to determine the blood's alcohol content level are reviewed, along with chemical test levels for Maryland DWI offenders. The guide explains how to operate the breathalyzer and proper testing procedures. It also describes the one exception when an individual may be compelled to take the chemical test and the method for chemically testing the blood. Suggestions for preparing a case consider checking for prior offenses, reviewing the charging document for errors, and handling the arresting officer's critical testimony. Also covered are videotape recordings, lay witnesses, and chemical test evidence. Problems faced by the attorney in prosecuting homicide by vehicle are explored, such as proving negligence and chemical testing. Finally, the manual surveys sentencing alternatives for convicted offenders and administrative sanctions. The appendixes provide a list of observable DWI actions and DWI offense forms.