How and why has medicine usurped legal and religious institutions when it comes to defining norms/deviance?

At the turn of the nineteenth to the twentieth century, in most secularised Western societies medicine substituted legal and religious institutions that used to hold the power to define deviant behaviors because it became a fully legitimized industry able to carry on the institutionalization of medical social control through the professionalization of medicine. The new perspectives on the conjunction of medical science, religion, and penal law changed the way that deviancy is defined.

Sociology, therefore, considers mental health professionals as agents of social control, whose diagnostic labels function as a way to enforce conformity to the existing social order.

Explanation:

For example, Alcoholism used to be defined as sin by religious institutions, and the rhetoric of A.A. was openly religious. However, in the present, alcoholism has been medicalized and is listed as a medical illness.