Criminal LawWhat is Criminal Law? What are the Basic Principles?

Criminal law is a branch of public law that regulates which acts constitute offences, the sanctions (penalties) to be applied to these offences and how these sanctions will be executed in order to protect the order and security of a society and the rights of individuals. As it is an area in which the State exercises its power to punish (ius puniendi), it is directly related to individuals’ rights to liberty and security. Therefore, criminal law strictly adheres to certain fundamental principles to prevent arbitrariness and ensure a fair trial process. In this article, we will examine in detail the definition of criminal law, its historical development, its basic principles and its place in the Turkish legal system.

Historical Development of Criminal Law: The understanding of criminal law has shown great changes throughout human history. In ancient times, the concepts of crime and punishment were generally based on the principles of revenge and retaliation. Even in the first written legal texts such as the Code of Hammurabi, certain punishments were prescribed for offences. In the Middle Ages, with the influence of religious and feudal authorities, punishments were generally aggravated in the form of bodily torture and the death penalty. With the Age of Enlightenment, under the influence of thinkers such as Cesare Beccaria, modern criminal law principles such as “legality in crime and punishment”, “proportionality” and “humanity” began to emerge. In the Turkish legal system, there has been a significant evolution with the transition from the sharia law and customary law practices in the Ottoman period to the modern criminal laws in the Republican period (Turkish Penal Code No. 765 dated 1926 and Turkish Penal Code No. 5237 dated 2005).

Basic Principles of Criminal Law (Detailed Explanation):

1. Principle of Legality (Nullum crimen, nulla poena sine lege): This principle is the most fundamental and indispensable principle of criminal law. It is clearly regulated in Article 38 of the Constitution and Article 2 of the Turkish Penal Code. Accordingly, in order for an act to be considered a criminal offence and for a penalty to be imposed for this act, the act must be clearly defined in the law and the penalty must also be specified in the law. This principle ensures the legal security of individuals by ensuring that they know in advance which of their behaviours are criminal offences. The sub-principles of the principle of legality are as follows:
   • Principle of Vagueness: Definitions of offences and penalties must be clear, precise and comprehensible.
   • Non-retroactivity of the Unfavourable Law: Subsequent laws that are against the defendant cannot be applied retroactively, even if they stipulate a heavier penalty than the law in force at the time of the offence. However, the favourable law shall be retroactive.
   • Prohibition of Comparison: An offence or punishment cannot be created by applying a situation not expressly regulated in the law to a similar situation by analogy.
   • Prohibition of the Administration to impose offences and penalties through regulatory acts: Offences and penalties can only be established by law; offences and penalties cannot be created by administrative regulations such as by-laws and regulations.

2. No Punishment Without Fault Principle: This principle states that in order for a person to be punished, he/she must be at fault for the act he/she has committed. In other words, the person must have committed the act knowingly and willingly (intention) or by breaching the duty of care and attention (negligence). A person who lacks the ability to perceive and will (for example, a mentally ill person or a very young child) cannot be punished. The Constitutional Court also recognises this principle as a requirement of the rule of law.

3. Principle of Individuality of Punishments: Criminal responsibility is personal. No one can be punished for an offence committed by another person. In the event of the death of a person, the criminal case against him/her shall be dropped and the penalties imposed shall not be passed on to the heirs. This principle is one of the cornerstones of modern criminal law.

4. Principle of Humanism: Human honour and dignity must be protected in the execution of sentences. Torture, ill-treatment, inhuman or degrading punishments are prohibited. This principle is also guaranteed by international human rights conventions.

5. Proportionality Principle: There must be a fair balance between the offence committed and the punishment and security measures imposed in response to this offence. The punishment must be appropriate to the gravity of the offence, the fault of the perpetrator and the social danger. This principle is frequently emphasised in the decisions of the Constitutional Court. For example, as stated in the decision of the Constitutional Court Decision No. E. 2020/91, K. 2021/73, the legislator is bound by the principle of proportionality, which is a requirement of the rule of law, when making regulations on criminal law. This principle consists of three sub-principles: convenience, necessity and proportionality.

6. Presumption of Innocence: A person is presumed innocent until his or her guilt is established by a final judgement of a court after a trial conducted in accordance with the law. This principle is a fundamental guarantee of the right to a fair trial and includes the principle of interpretation of suspicion in favour of the accused (in dubio pro reo).

7. Rule of Law Principle: It is the principle that the State is bound by law in all its actions and transactions, preventing arbitrariness and ensuring the legal security of individuals. Criminal law is one of the most concrete application areas of the rule of law principle. As stated in the CONSTITUTIONAL COURT DECISION E. 2006/154, K. 2009/35, the rule of law is the state whose actions and transactions are in accordance with the law, which is based on human rights, which protects and strengthens these rights and freedoms, which establishes and maintains a just legal order in every field, which ensures legal security, which complies with the law and the Constitution in all its activities, and whose actions and transactions are subject to independent judicial review.

Sources of Criminal Law: The main sources of Turkish criminal law are as follows:

• Constitution: It determines fundamental rights and freedoms and principles of criminal proceedings.
• International Conventions: International treaties, such as the European Convention on Human Rights, are part of our domestic law and affect criminal law practices.
• Turkish Penal Code (TCK): The basic law that regulates offences and punishments in general and special provisions.
• Criminal Procedure Code (CPC): It regulates how criminal proceedings will be conducted and the investigation and prosecution processes.
• Other Special Criminal Laws: Special laws such as the Anti-Smuggling Law, the Law on Firearms and Knives and Other Instruments also include specific offences and punishments.

Distinction between Substantive Criminal Law and Formal Criminal Law: Criminal law is generally divided into two main branches:

• Substantive Criminal Law: It regulates which acts are offences, the penalties and security measures to be applied to these offences, the conditions of criminal responsibility and the cases of impunity (Turkish Penal Code).
• Formal Criminal Law (Criminal Procedure Law): It regulates how the state will exercise its power to punish when a suspicion of a crime arises, the investigation and prosecution processes, the collection and evaluation of evidence, and remedies (Criminal Procedure Law).

These two fields are closely interrelated; while substantive criminal law defines offences and punishments, formal criminal law shows how these definitions are to be applied.

Criminal law is one of the pillars of a modern rule of law. It serves the dual purpose of ensuring social order and security while securing the freedoms of individuals. Its fundamental principles guarantee a fair trial and execution process by preventing arbitrariness. A good understanding of these principles is of great importance for both law practitioners and citizens. In accordance with the rule of law, it is essential to comply with the principle of proportionality and to observe a fair balance between offence and punishment when making regulations on criminal law.