Centralisation without Independence: The functional scope of informal intergovernmental organisations

Informal intergovernmental organisations (IIGOs) like the G20, the G7, and BRICS have become key pillars of the post-Cold War multilateral system. IIGOs lack a legal foundation and a permanent secretariat or staff—yet states now use them to govern global issues ranging from artificial intelligence to nuclear non-proliferation. This raises a critical question: are IIGOs viable vehicles for supporting sustained and structured state interactions? I address this question by theorising IIGOs’ functional scope. Building on the institutional design literature, I disaggregate the notion of formality into organisational properties (P)—centralisation and independence—and relate these to organisational functions (F). Because IIGOs lack independence from member states but may achieve centralisation, the P-F framework suggests that IIGOs can enhance negotiation stability, information dissemination, and issue linkage. In turn, they struggle to support cooperation through initiation and enforcement. A case probe of the G20’s organisational structure and operations lends plausibility to these conjectures.