More knowledge is needed on how to reduce the prevalence of formal and informal coercion in Norwegian mental health care. To explore possible reasons for the widespread differences in coercive practice in psychiatry and drug addiction treatment in Norway, and the poor compliance to change initiatives, we performed a nationwide survey. Six vignettes from concrete and realistic clinical situations where coercive measures were among the alternative courses of action, and where the difference between authoritarian (paternalistic) and dialogical (user participation) practices was explicitly delineated, were presented in an electronic questionnaire distributed to five groups of professionals: psychiatrists, psychologists, nurses, other professionals and auxiliary treatment staff. Non-coercive dialogical resolutions were more likely than coercive authoritative. However, there is a clear professional hierarchy with regard to authoritarian approaches, with the psychiatrists on top, followed by nurses and other professionals, and with psychologists as the least authoritarian. The majority of the respondents sometimes prefer actions that are illegal, which suggests that individual opinions about coercion often overrule legislation. The variation between and within professional groups in attitudes and opinions on coercion is extensive, and may account for some of the hitherto meagre results of two ministerial action plans for coercion reduction.