This book belongs to the field of criminal law in both its substantive and procedural branches, specifically addressing the procedural aspect. It explores the stages of criminal proceedings, starting from the evidence-gathering phase, passing through the preliminary investigation phase, and concluding with the trial stage. The book begins by outlining the framework within which criminal procedures operate, focusing on the parties involved, the termination of criminal cases, and the limitations imposed on such proceedings. It then devotes a first section to the evidence-gathering phase, clarifying the powers of law enforcement officers and the restrictions placed upon those powers. Following that, it explains the powers of the Public Prosecution during investigations and the course such investigations may take, whether they result in dismissal or referral to the court. A third section is dedicated to the trial phase, beginning with an explanation of the jurisdiction of criminal courts in Qatar and the procedures of the trial. It details the scope of the case before these courts and the characteristics of criminal trials, concluding with a focus on the theories of evidence and procedural nullity.