The international law, I think, is that we try to use by analog what we've always understood about law of armed conflict with people directly in control of the weapons. In domestic space there are interesting challenges in trying to de-conflict users of the airspace. In my paper I tried to talk a bit about that. In Canada, Transport Canada issues what they call special flight operations certificates for specific flights or specific flight regimes. Those flights have to be programmed. They have to be described. In separating flight, when there are pilots aboard, it's all see and be seen, or we have air traffic controllers who ensure that we don't get too close to one another and that there is no conflict.
Among the UAV crowd, that air traffic control could apply. But if it's uncontrolled airspace, and a lot of Canada is uncontrolled, there really isn't a good way of managing that. So we just carve off regimes of airspace and say, “You can go and fly in that place and no one else can.”