In this paper we study the rational balance between local and global policies in web based distributed systems. We use a logical framework for multiagent systems to model obligations and permissions composing policies. In particular, a qualitative decision theory allows agents to trade off the decision of respecting a norm against the consequences of not respecting it: the possibility that they are considered violators and thus sanctioned. Global policies refer not to the existence of a local norm but to the fact that it is enforced by the local authority by recognizing and sanctioning violations.