[1] Neofunctionalism seeks to explain the European integration process[2] and why states accept to become a part of supranational organization.
This reflects the continued relevance and adaptation of neo-functionalism in understanding how states engage with and support supranational organizations, particularly within the context of European integration.
Haas theorized three mechanisms that he thought would drive the integration forward: positive spillover, the transfer of domestic allegiances and technocratic automaticity.
[11] Neofunctionalism was modified and updated in two important books that helped to revive the study of European integration: European Integration and Supranational Governance (1998) by Wayne Sandholtz and Alec Stone Sweet,[13] and The Institutionalization of Europe (2001) by Sandholtz, Stone Sweet, and Neil Fligstein.
[14] Sandholtz and Stone Sweet describe and assess the evolution of Neofunctionalist theory and empirical research in their 2009 paper, Neo-functionalism and Supranational Governance.
[15] Despite its profound insights in regional integration, neofunctionalism is widely criticized at an empirical level for failing to account the reality of the European Communities.
The theory rejects the spillover-effect argument and the idea that supranational organisations wield political influence on par with that of national governments.