In Sweden an oral hearing, the trial, is held as the ideal model for the criminal procedure and according to the legality principle reported crimes ought to be investigated and prosecuted. Over time high levels of reported crimes have led to an increase in pressure on the courts and other actors in the criminal process. This pressure has created new ways of dealing with reported crimes in summary procedures and to exceptions from the legality principle. Such changes have given the prosecutor a key role in deciding how cases are dealt with in the criminal process.  The purpose of this thesis is to examine the Swedish public prosecutor’s influence on the choice of cases that are investigated, prosecuted and tried in court during a trial. The study examines the prosecutors’ legal authority and how that authority has changed from the time that the Code of Judicial Procedure came into force in 1948 to the beginning of 2011. A starting point for the examination is that investigating, prosecuting and trying cases in the criminal process should be carried out in a way that is considered to be fair according to societal values, which are embedded in the legal system. Both decisions about which cases will be tried and the procedure involved in how to try them has to be performed in a way that seems to be fair. In the study the values that underlie the criminal process is examined through a model. This model assumes that the criminal process has been created and developed to satisfy different requirements, which can be separated into three main groups: the functions of the criminal process, legal principles and the main objectives of a good administration of justice. The model is used to analyze and discuss the development of the legal rules. The prosecutor’s authority and influence over the process has broadened and the use of summary procedures has served to place the focus on the police investigation instead of the trial. Among the objectives of a good administration of justice Speed and Cost effectiveness are considered to be more important than Security. As long as the Trust in the system is sufficient this development can continue. A conclusion from the study is that there is a need for some actor to prioritize and to do that openly. In the study the issue is raised whether it is time to question the legality principle as the main principle for the Swedish legal system. / <p>Förlagsutgiven med 3 månaders embargo.</p>