A network of professionals with recognized expertise and competence in a particular domain, and an authoritative claim to policy-relevant knowledge within that domain or issue-area.
(Haas, Peter. 1992. "Epistemic Communities and International Policy Coordination." International Organization 46(1): 1-35, p.3)
Haas writes that "the professionals in a particular epistemic community may come from different disciplines and backgrounds, but must have:
1.) A shared set of normative and principled beliefs which provide a value-based rationale for the social action of community members.
2.) Shared causal beliefs, which are derived from their analysis of practices leading or contributing to a central set of problems in their domain and which then serve as the basis for elucidating the multiple linkages between possible policy action and desired outcomes.
3.) Shared notions of validity that is, inter subjective internally defined criteria for weighing and validating knowledge in the domain of their expertise.
4.) A common policy enterprise- that is, a set of common practices associated with a set of problems to which their professional competence is directed, presumably out of the conviction that human welfare will be enhanced as a consequence."
Leslie Pal writes that this concept originally developed in the field of international relations. Pal states that this concept tries to capture the influence of international groups of scientific experts on policymaking; for example, in the environmental field. Within an epistemic community, there is emphasis on the power of ideas and expertise, as expressed through professional organizations or individuals.