Criminal law deals with the investigation and prosecution of acts that constitute crimes. In Turkey, when an investigation is initiated against a person, evidence is collected by the prosecutor's office and the prosecution stage begins according to the nature of the crime. The suspect or defendant has rights in this process: the right to have a lawyer, the right not to testify, the right to defense, etc. In serious criminal cases, the pre-trial and trial process is longer and more complex. Clients can ensure the protection of their rights by receiving legal counsel during this process. Lawyers manage the defense by assuming representation duties during investigation and prosecution stages and ensure proper evaluation of evidence.