# Bouncer > Does someone look like a troublemaker? Primary [Arbiter](https://github.com/rbkmoney/bouncer-proto/blob/97dcad6f/proto/decisions.thrift#L42) thrift service implementation. In a nutshell this service maps incoming contexts into [OPA input documents](https://www.openpolicyagent.org/docs/latest/philosophy/#the-opa-document-model) and asks OPA to compute a set of assertions allowing or forbidding actions under given input context. From the service's point of view a **ruleset id** is a path to OPA document that define a subdocument named `assertions` with a rudimentary schema. See https://github.com/rbkmoney/bouncer-policies#authoring for more detailed information.