Normative systems have been advocated as an effective tool to regulate interaction in multi-agent systems. The use of deontic operators and the ability to represent defeasible information are known to be two fundamental ingredients to represent and reason about normative systems. In this talk I will introduce a framework that combines standard deontic logic (SDL) and non-monotonic logic programming, deontic logic programs (DLP), to represent and reason about normative systems. Besides having a rich language, DLPs have a simple and fully declarative semantics. In fact, a stable model like semantics can be defined for these programs and abduction can be used to allow agents to plan their interaction with the normative system. The fundamental problem of equivalence between normative systems is studied using a deontic extension of the so-called equilibrium logic. Furthermore, I will present a novel strong connection with the so-called Input-Output logic. Joint work with José Alferes.