Although SIU, in its judicial capacity, depends primarily on the complaints received or submitted to it by the concerned parties that include incidents that fall within its competence, but given the nature of its tasks related to a significant aspect of human rights, SIU also takes it upon itself to monitor incidents or allegations of torture, abuse or cruel treatment from: what is published and broadcasted in the audiovisual media, circulated on social networking platforms and the Internet, or what is it may come to its knowledge from any other source. SIU initiates contact with the concerned victims, witnesses, and anyone who has information, and proceeds with its necessary investigative procedures, with the assistance of its specialized divisions. In criminal investigation, SIU relies on several basic legal references, as follows:
- The Penal Code, which regulates offences against persons, torture, sexual and physical assault, threats, humiliation and insults, and related offences included in the Penal Code or any other law.
- The Code of Criminal Procedure as for guarantees and procedures for interviewing and hearing witnesses, issuing judicial orders, conducting inspections, and dealing with seizures, as well as initiating lawsuits before the courts, challenging and executing rulings.
- Istanbul Protocol (Investigation and Documentation of Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment).
- SIU Instructions, which are integrated guidelines, consist of six chapters and 66 Articles. It specifies the nature of the Unit, its objectives, authorities entrusted to it, competencies, formation, tasks of its sections and divisions, duties of its members and affiliates and characteristics that they should possess, means of collecting verbal, material and technical evidence, and what procedures must be followed in this regard. The instructions were drawn up by one of the UN eminent experts, and they were prepared in the light of the provisions of the law and the new legal principles, and based on the rules established in Istanbul Protocol. It is also formed based on relevant international instruments, in particular the Convention against Torture and Other Cruel or Degrading Treatment or Punishment, declarations, rules, principles, guidelines, codes of conduct, such as Code of Conduct for Law Enforcement Officials, Basic Principles on the Use of Force and Firearms by Law Enforcement Officials and Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment.