The cooperation between intelligence and security services has increased and undergone innovation, while collaboration among oversight bodies is still developing. A joint project began in 2015, where oversight bodies from five countries conducted similar investigations within their national contexts and frameworks, comparing their findings. The focus of this investigation was on the exchange of data regarding (alleged) jihadists between intelligence and security services. The CTIVD published a report on this investigation on 28 March 2018.

Between 2016 and 2018, the oversight bodies from Belgium, Denmark, Norway, Switzerland, and the Netherlands exchanged experiences from their national investigations, leading to a deeper understanding and a more comprehensive view of international cooperation in intelligence and security. The oversight bodies identified a potential 'oversight gap,' as oversight of international cooperation remains largely national. They collectively urged national legislators to address the primary barrier to cooperation, which is the secrecy surrounding the activities of intelligence and security services in this domain. The five oversight bodies plan to maintain close collaboration, sharing best practices and discussing relevant issues.

In 2019, the British oversight body joined this collaborative effort. The partnership's meetings focus on current legal and technical concerns pertinent to the participating oversight bodies and on exchanging best practices in oversight, with an emphasis on enhancing oversight methods. In December 2019, six oversight bodies signed a charter formalizing their cooperation under the name Intelligence Oversight Working Group, with the CTIVD serving as the secretariat until May 2020.

In October 2022, two Swedish oversight bodies were added to the Charter, becoming part of the Working Group.

Cooperating oversight bodies

  • Belgian Standing Intelligence Agencies Review Committee (Comité permanent de contrôle des services de renseignements et de sécurité / Vast Comité van Toezicht op de inlichtingen- en veiligheidsdiensten) – www.comiteri.be (Belgium);
  • Danish Intelligence Oversight Board (Tilsynet med Efterretningstjenesterne) – www.tet.dk (Denmark);
  • Review Committee on the Intelligence and Security Services (Commissie van Toezicht op de Inlichtingen- en Veiligheidsdiensten) – www.ctivd.nl (The Netherlands);
  • EOS Committee – The Norwegian Parliamentary Intelligence Oversight Committee (EOS-utvalget) – www.eos-utvalget.no (Norway);
  • Swedish Commission on Security and Integrity Protection (Säkerhets- och integritetsskyddsnämnden) – www.sakint.se  (Sweden);
  • The Swedish Foreign Intelligence Inspectorate (Statens inspektion för försvarsunderrättelseverksamheten) – www.siun.se (Sweden);  
  • Independent Oversight Authority for Intelligence Activities (OA-IA) (Unabhängige Aufsichtsbehörde über die nachrichtendienstlichen Tätigkeiten AB-ND) – www.ab-nd.admin.ch (Switzerland);
  • Investigatory Powers Commissioner's Office – www.ipco.org.uk (United Kingdom);
  • National Security and Intelligence Review Agency - National Security and Intelligence Review Agency - Official Website (Canada).