The field of criminal procedure provides part of the matrix of fairness and justice which promotes equality of treatment for persons accused of crime and, therefore, occupies an important position in the field of criminal justice. Since its genesis comes from both the Constitution of the United States and the constitutions of the several States, its substance and application will vary in some fashion from jurisdiction to jurisdiction. The decisions made by the Supreme Court of the United States, when speaking on federal constitutional issues, are binding on state criminal justice practice. Although constitutional decisions are mandatory on the states, such decisions dictate the minimal legal protections required under our federal system. Every state may go beyond the basic federal guarantees by offering an accused greater state constitutional rights and may grant enhanced criminal procedure protections based on state constitutional and statutory law. The constitutional and statutory rules that make up the body of law known as criminal procedure regulate the way both state and federal governments must treat persons accused or suspected of committing crimes, Rules dictating the way law-enforcement officials interact with individuals who are mere suspects for particular crimes restrain the activities and approaches that can be followed prior to the initiation of formal criminal prosecutions. When investigations have moved beyond their initial stages to the point where criminal suspects have been identified, the rules of criminal procedure provide a road map which all law enforcement officials must follow. Where law enforcement officials fail to observe recognized criminal procedural rules, such deviation may jeopardize any eventual successful criminal prosecution by opening the conviction to appellate attack. Similarly, when the law enforcement officials have turned their work product over to the prosecutor's office, the personnel presenting the government's case must carefully follow additional rules regulating fair conduct in order to accord due process to criminal accused. Defense attorneys have a role within the rules of criminal procedure to insure that the government has played fairly during the investigation, pretrial and trial phases and the attorneys for defendants possess an obligation to provide a vigorous defense consistent with the Constitution and state rules and regulations. During criminal trials, judges must carefully weigh the arguments of the contending parties, whether they are arguing over criminal procedural issues relative to the admission of evidence or whether the attorneys are contending over more traditional admission of evidence under evidence codes. Whether a judge presides over pretrial issues, the trial itself, post-trial motions, or serves on an appellate panel reviewing what trial level judicial decisions, every judge possesses a duty of due process to both the prosecution and to the defense. Roughly translated, due process implies fundamental fairness and fair dealing during all important portions of the criminal justice process. The study of criminal procedure traditionally follows a case method of instruction where the students read previously decided criminal cases which instruct by using concrete examples covering criminal procedure issues. The largest developments and changes and corrections in the criminal procedure have generally come from landmark case decisions of the Supreme Court of the United States. Implementation of the rules contained within Supreme Court case decisions has largely been delegated to state legal systems where state courts have developed slightly divergent interpretations and applications of these legal principles. The Federal Rules of Criminal Procedure and state rules of criminal procedure owe much of their content to the codification of legal principles announced by the Supreme Court of the United States and to common law practice. WhileIngram, Jefferson is the author of 'Criminal Procedure Theory and Practice', published 2004 under ISBN 9780130987600 and ISBN 0130987603.