Abstract
This paper proposes a two tier RBAC approach for secure and selective information sharing among virtual multi-agency response team (VMART) and allows expansion of the VMART by admitting new collaborators (government agencies or NGOs) as need arise. A coordinator Web Service for each member agency is proposed. The coordinator Web Service is responsible for authentication, information dissemination, information acquisition, role creation and enforcement of predefined access control policies. Secure, selective and fine-grained information sharing is realized through the encryption of XML documents according to RBAC policies defined for the corresponding XML schema.