There are certain behaviors in society that are considered to be in violation of the established laws. In order to maintain law and order, the legal structure of the country criminalizes such behaviors. Criminal law serves as a principal tool to combat crime, punish and reform the criminals, and maintain the law and order in the society. Criminal justice systems refer to the government agencies that are responsible for enforcing law, adjudicating crime and correcting criminal conduct. These agencies have been established for maintaining social control and introducing reforms. Law enforcement, prosecution, courts, corrections and rehabilitation are important constituents of the criminal justice system. Its primary objectives are to prevent the occurrence of the crime, to punish and rehabilitate the transgressors, compensate the victims, and deter the criminals from indulging in unlawful acts in the future. In the United States, exclusionary rule is a constitutional law that prevents evidence obtained by the government in violation of a defendant's constitutional rights from being used in a court of law. This book presents studies related to criminal justice systems and the exclusionary rules which are of utmost significance in modern times. Its extensive content provides the readers with a thorough understanding of the subject.