Criminal law is a section of public law that analyses the concepts of crime and punishment. It is divided into two as general and special criminal law (also referred to as general and special criminal law).
The subject of general criminal law is the definition of the concept of crime with its material and moral elements, the general principles that dominate criminal law, the definition of the concept of punishment, the reasons that eliminate the crime, the reasons that reduce and eliminate the punishment, and the principles and theories that apply to all crimes. The subject of special criminal law is the acts that are considered as offences according to the laws of the country, their scope and limits, their different aspects and the penalties prescribed for these offences. While criminal law includes criminal procedure in a broad sense, criminal procedure in a narrow sense is outside the scope of criminal law.
The two most important principles of criminal law are the principle of legality in crime and punishment and the principle of fault in crime and punishment.
1. The principle of legality in crime and punishment (nulla poena sine lege)
The offence and its corresponding punishment can only be determined by law. This fundamental principle is enshrined in paragraph 1 of Article 2 of the Turkish Penal Code No. 5237: "No one can be punished or imposed security measures for an act that the law does not explicitly criminalise." This requires the definition of offence to be clearly and explicitly regulated by law. An offence cannot be defined with vague and ambiguous expressions (nulla poena sine lege certa). Another condition required by the principle of legality is that an unfavourable law cannot be retroactive. In other words, no one can be punished for an act that was not an offence at the time it was committed, on the grounds that the act was subsequently criminalised (nulla poena sine lege praevia). Another condition imposed by the principle of legality is the prohibition of comparison against the perpetrator. In legal science, syllogism refers to the filling of a gap in the law by finding the most similar rule of law. In criminal law, syllogism cannot be applied (nulla poena sine lege stricta) as it is stated in paragraph 3 of Article 2 of the Turkish Criminal Code No. 5237 as "No syllogism can be made in the application of the provisions of the laws containing offences and penalties."
2. The principle of fault in offence and punishment
Fault, in the sense of criminal law, is the intentional and knowing commission of an act by a person capable of attribution. In other words, the perpetrator must have done the act knowingly and willingly in order to be punished. From this principle, the principle that only the perpetrator who has committed the act himself can be punished is derived. This principle is also included in paragraph 1 of Article 20 of the Turkish Penal Code No. 5237: "Criminal responsibility is personal. No one can be held responsible for the act of another."