The criminal law systems have been central to the attempts of modern states to avert, research and convict terrorism in the context of national security paradigms. The research paper critically analyzes both substantive and procedural aspects of criminal law procedures used in counter-terrorism, and the way in which the legal frameworks address the demands of effective security in accordance with the human rights, legality, and due process provisions. Starting with a discussion of legal definitions and the broadening of terrorist related crimes, the research emphasizes the reasons why broad or non-specific language may increase the scope of criminalization of crimes beyond violent behaviours to preparatory and supportive actions. It also covers preventive detention, longer investigation authority, special procedural accommodations in court, and surveillance authorities that increase state ability in disrupting terror networks at the expense of arbitrary implementation and reduced procedural protection. The study is a synthesis of the doctrinal study and comparison perspectives and human rights critique that indicated that there were enduring tensions on state security goals and civil liberties. Social and psychological aspects are also taken into consideration showing how the criminal law can be used to influence the levels of community trust, social cohesion, and perceptions of justice. It highlights the significance of the judicial review, accuracy in the drafting of legislation, and incorporation of proportionality concepts to reduce the risk of abuse and violation of rights. Some of the policy recommendations include the definition of offences, enhancement of the monitoring processes, instillation of human rights, and the involvement of communities to develop trust and obedience. The paper is relevant to the body of literature since it provides an extensive discussion of the role of criminal law in counter-terrorism and presents reform directions that can ensure the national security and the rule of law