This college text examining the entire American system of criminal justice with particular emphasis on local law enforcement and the role of the modern police officer. The role of the modern police officer is brought sharply into focus in this study of the criminal justice system. The emphasis throughout is on local law enforcement and the problems and challenges which the individual officer must meet. The book is divided into five parts, the first of which discusses crime causes, foundations of criminal law, and the evaluation of law enforcement in America. Concepts of modern police organization and management are introduced. The next part explains the primary operational functions of the local police department, including patrol, traffic operations, criminal investigation, and prevention and control of juvenile delinquency. Constitutional aspects of law enforcement are explored, particularly landmark court cases which have had significant impact upon police practice and philosophy. Individual chapters in this section address themselves to issues of police professionalism and the policeman's image in official and private life. The final part of the book takes a look at changing concepts in police management including selection and training of police officers. The individual officer's viewpoint is again pursued in a discussion of career development opportunities, advances in personnel methods, and new trends in law enforcement.