The Five Eyes is an intelligence alliance comprising Australia, Canada, New Zealand, the United Kingdom, and the United States. These countries are parties to the multilateral UK-USA Agreement, a treaty for joint cooperation in signals intelligence. The Five Eyes can also refer to the group of intelligence agencies of these countries. The Five Eyes alliance is sort of an artifact of the post-World War II era where the Anglophone countries are the major powers banded together to sort of co-operate and share the costs of intelligence gathering infrastructure. The Five Eyes agreement stands out from other arrangements because the parties are diverse societies, governed by rule of law and robust human rights and are bonded by a common language. These characteristics aid the partners in sharing information with one another to protect their shared national interests.

The Five Eyes intelligence-sharing arrangements are shrouded in secrecy, allowing for arbitrary or unlawful intrusions on the right to privacy which circumvent domestic legal restrictions on state surveillance. There is no domestic legislation governing intelligence-sharing, meaning that many of these arrangements lack legal basis and therefore democratic legitimacy. The Five Eyes states conduct interception, collection, acquisition, analysis, and decryption activities, sharing all intelligence information obtained with the others by default.

The Five Eyes Intelligence Oversight and Review Council (FIORC) is composed of the following non-political intelligence oversight, review, and security entities of Australia, Canada, New Zealand, the United Kingdom, and the United States:

• The Office of the Inspector-General of Intelligence and Security of Australia
• The National Security and Intelligence Review Agency of Canada
• The Office of the Intelligence Commissioner of Canada
• The Commissioner of Intelligence Warrants and the Office of the Inspector-General of Intelligence and Security of New Zealand
• The Investigatory Powers Commissioners Office of the United Kingdom
• The Office of the Inspector General of the Intelligence Community of the United States

The Five Country Ministerial is a forum for the Five Eyes security ministers to meet and discuss opportunities for collaboration. Topics cover the full range of public safety and national security issues facing each of the Five Eyes partners. The Five Country Ministerial can also include a joint meeting between the Five Eyes security ministers and the Quintet of the Attorneys General (also called “the Quintet”) in order to bridge discussions between these two groups. The Quintet is a group composed of the Attorneys General of the Five Eyes partners, who work to advance legal matters of shared importance.