When you deploy RD, you deploy under what is called Rules Of Engagement (ROE), each military force will have certain ROE types, just as the UN also have one. Basically what an ROE card is, is the laws of what you can, and cannot do, in a specific operation depending on what they classify a zone to be. For example: aid missions may be no weapons, or if weapons are present, the lowest ROE meaning there is no direct enemy. It obviously steps up from there to warlike situations. The UN have standard laws in which are given to every soldier deployed within a UN mission, which outline the laws of conflict for that operation. Sometimes they are the same, sometimes they change, depending on each situation uniquely.
So, soldiers are briefed and made aware of the laws of conflict to an International level, and they carry them upon them in a brief form if under UN control.