Abstract The gate‐keeping function that physicians perform in determining clients’ physical and mental incapacities is widely assumed to be the main reason for the rising numbers of disabled people. The sharp rise in the number of disabled has led many to claim that the disability benefits schemes are untenable. In order to regain public control and to make disabled eligibility procedures more transparent guidelines have been introduced in which medical evaluations are conceptualised as formal rational decisions. It is, however, questionable whether such measures are helpful in achieving their stated aims. This paper is based on ethnographic research on the ways physicians evaluate the eligibility of clients for disability benefits. It argues that assessing incapacity involves much more than formal rational decision‐making. Doctors’ reasoning is contextual and deliberative in character, and thus their assessment of a client's incapacity is less a technical matter than a normative one. Instead of generating transparency, guidelines based on formal rationality make the complex deliberations on which such judgments are based invisible, because they deny the normative dimension of medical expert decision‐making. Therefore, different measures have to be developed that allow this normative dimension to be articulated, since insight into this normative dimension is a necessary pre‐condition to be able to criticise disability judgments at all.