THE PROBABILITY THAT A DRINKING DRIVER WILL BE STOPPED BY A POLICE OFFICER IS CONSIDERED AND DETECTION METHODS AVAILABLE TO THE OFFICER--OBSERVING DRIVING BEHAVIOR, OBSERVING THE BEHAVIOR OF DRIVERS WHO HAVE BEEN STOPPED FOR NONMOVING VIOLATIONS OR WHO HAVE BEEN STOPPED FOR NONMOVING VIOLATIONS OR WHO HAVE BEEN INVOLVED IN TRAFFIC ACCIDENTS--ARE DISCUSSED. DETECTION OPPORTUNITIES AT FOUR STAGES--PRIOR TO APPREHENSION, DURING THE PROCESS OF APPREHENSION, DURING PREARREST INVESTIGATION, AND DURING INVESTIGATION OF TRAFFIC ACCIDENTS--ARE POINTED OUT. DRIVING AND PERSONAL BEHAVIOR CHARACTERISTIC OF DRINKING DRIVERS IS DESCRIBED. GUIDELINES FOR DECIDING ON AN ENFORCEMENT ACTION ON THE BASIS OF DETECTION EFFORTS ARE OFFERED, TOGETHER WITH A FLOWCHART ILLUSTRATING THE ENFORCEMENT DECISIONMAKING PROCESS. A 22-PAGE CHART LISTS DETECTION CLUES FOR THE IDENTIFICATION OF DRIVING WHILE INTOXICATED (DWI) DRIVERS AT EACH OF THE PHASES NOTED ABOVE. ANSWER-KEYED QUESTIONS ARE INCLUDED AS STUDY AIDS. FOR OTHER MARYLAND TRAINING DOCUMENTS ON DWI PROCEDURES, SEE NCJ-52080, 52081, 52083, AND 52084. (LKM)