Criminal procedure refers to the mechanisms under which crimes are investigated, prosecuted, adjudicated, and punished, and includes the protections of the accused persons’ constitutional rights. This reference guide on contemporary criminal procedure assists law enforcement officers to deal with the issues that they may encounter in their communities. It gathers into a handbook format some of the most important U.S. Supreme Court decisions to aid officers in understanding the nature and impact of these decisions and acts as a tool for officers in decisions in their everyday work. The guide considers 14 areas where the Court has made important decisions about police conduct. In making these decisions, the Court must balance the protection of individual rights of citizens with the need for effective law enforcement. The 14 areas or chapters were selected because they are considered particularly troublesome for police and prosecutors and courts of law. The 14 chapters include: (1) arrests and entry to make arrests; (2) detention and searches of persons; (3) search and seizure defined; (4) search incident to arrest; (5) vehicle searches; (6) consent to search; (7) “plain view” and “plain feel” doctrines; (8) inventory searches; (9) “open fields,” cartilage, and aerial surveillance; (10) “exclusionary rule” and “fruit of the poisonous tree;” (11) police interrogation; (12) probable cause; (13) use of informants; and (14) entrapment.