The 10th Tallinn Paper authored by Katrin Nyman Metcalf offers a legal view on outer space and cyberspace: similarities and differences. It is not unusual in academic or practical debate to compare outer space and cyberspace – in both cases dealing with areas that appear borderless, which means that traditional legal principles and rules based on state jurisdiction within specific borders, cannot apply or at least will be difficult to apply. Consequently, lawyers and others dealing with these areas will have to think creatively and be willing to apply a functional way of reasoning rather than a strictly rule-bound one. Author of the analyses suggests that the two areas of law still show evidence of similarities as well as differences that can be useful to observe and mutually learn from. It might appear as if outer space law as the “older sibling” has less to learn, but in fact this area of law is currently in an important process of change, due to developments that have occurred in space in recent decades. The most significant of these changes is the privatisation of space activities. As cyberspace has been predominantly private from the beginning, there can be useful lessons from cyberspace law. Above all, there are common issues of the two spaces related to the process of making law as well as to ensuring its implementation, in areas that challenge traditional notions of jurisdiction, authority of specific organisations and relationships between the public and private, the civilian and the military, the foreign and the domestic.