The paper offers an extensive theoretical discussion of and a contribution to the highly relevant, controversial, and normatively charged debate on the legitimacy of interest groups as non-elected, self-appointed representatives. The contribution of this paper is twofold. First, the paper juxtaposes two diverging approaches on legitimacy of interest groups, namely responsiveness as a means to achieve a congruence of interests and reflexivity as the structural facilitation of evaluative judgements conducted by the constituency. Second, the paper proposes a framework on institutional instruments generating reflexivity suitable for empirical research. To corroborate this concept-specification of reflexivity, this paper debates several empirical studies on and theoretical approaches to institutional mobilisation mechanisms enabling a structural facilitation of contestation. Eventually, three distinct attributes of the concept of interest group reflexivity are established. An interest group’s forums for exchange and education, its decision-making system and its grassroots involvement ought to ensure internal structural reflexivity towards its constituency. When combined, they can mitigate the potential for undemocratic representation due to a lack of or skewed mobilisation and empowerment.

Debates on the issue of representation have since long started to transcend elections and topographically bound constituencies by addressing self-appointed representatives in form of interest groups. However, with no elections and a mere claim to represent a constituency, who gets to judge and consequently authorises the claims and demands accountability? Deriving from Saward’s constructivist approach on the representative claim, this article introduces a revisited approach to interest groups by adjusting constructivism with respect to crucial insights derived from interest group theory, provided by Montanaro and Strolovitch. Building on this revisited approach, this article re-evaluates questions on who gets to authorise and account representatives and consequently presents a holistic constructivist framework not only on the nature of claim-based representation, but also on its potential and pitfalls. Additionally, it provides incentives for research on the disjunction between constituency and interest groups provoked by a (structural) occurrence of non-authorisation and non-accountability.