My thesis provides a comprehensive examination of the intersection between international law and counterterrorism. It thoroughly explores the concept of terrorism, analyzing it from the perspectives of international criminal law, crimes against humanity, and war crimes. The thesis highlights the complexities and limitations of current international anti-terrorism conventions and statutes, emphasizing the need for more robust and comprehensive legal frameworks. By comparing the legislative and institutional measures of the US and EU, it underscores the necessity for enhanced international cooperation and coordination to effectively combat terrorism. Overall, the thesis offers valuable insights into the challenges and potential strategies for improving global counterterrorism efforts