Ostiary is a security gem for your (rails) controllers & actions. It employs a before_filter-like call to set policies per controller/action. You can pass your own security call in block and handle the PolicyBroken yourself. Policies are also inherited from parent classes. From wikipedia: "An ostiarius, a Latin word sometimes anglicized as ostiary but often literally translated as porter or doorman, originally was a servant or guard posted at the entrance of a building. See also gatekeeper."