Many standards exist to formalize legal texts and rules. The same is true for legal ontologies. However, there is no proof theory to draw conclusions for these ontologically modeled rules. We address this gap by the proposal of a new modeling of deontic statements, and then we use this modeling to propose reasoning mechanisms to answer deontic questions i.e., questions like “Is it mandatory/permitted/prohibited to...”. We also show that using this modeling, it is possible to check the consistency of a deontic rule base. This work stands as a first important step towards a proof theory over a deontic rule base.