This Thematic Brief examines the use of counterintelligence and law enforcement powers in the intelligence sector. It considers the similarities and differences between the two, explores how such powers are applied by intelligence services, and identifies the main challenges to defining an optimal model for the use of law enforcement and counterintelligence powers by intelligence services, including:

• the clear delineation of competencies between different security agencies;
• the avoidance of overlaps and redundancies in the powers and functions of agencies with law enforcement and counterintelligence mandates;
• the introduction of comprehensive internal and external oversight systems; 
• and the establishment of an effective framework for interagency cooperation. 

This Thematic Brief is intended to assist states in the process of reforming their intelligence services. Composed of five parts, it explores the relationship between counterintelligence and law enforcement, including as regards functional similarities and differences, processes for transferring powers between the two, and the use of pre-trail investigations. It concludes with reflections on suitable models for defining the authority, role and functions of intelligence agencies in relation to law enforcement powers.