Medical priority-setting has been discussed heatedly in Sweden since the 1990s. While criteria such as medical need, solidarity and cost-effectiveness were established long ago, they failed to give clear directives to decision-makers on how to apportion priority. The notion of individual responsibility for one’s health was suggested as one solution out of the impasse. According to the responsibility principle, anyone who fails to live up to the norms of a healthy lifestyle can legitimately be given lower priority. Although the principle is gaining support, its effectiveness is being hampered by structural problems. We have analysed official reports and pertinent fora of the Swedish debate on priority-setting from the period 1990–2009 and have examined the responsibility principle using a Luhmannian framework. Unlike common criticism emphasizing difficulties of assessing whether individuals can actually be held accountable for their lifestyle, we found that the responsibility principle fails in its current form because it unifies two incompatible logics deeply rooted in the functionally differentiated structure of society: those of medical reasoning (connecting health condition with lifestyle) and political expediency (attributing responsibility). We conclude that future policy-making cannot simply overlook this conflict, but has to acknowledge its presence and constructively utilize its potential.