Harold Koh, Legal Adviser to the State Department, delivered an important speech yesterday, September 18, at the U.S. Cyber Command Inter-Agency Legal Conference on the applicability of international law to cyberspace. (H/T to Opinio Juris, which has posted the speech in full text.) Organized in a straightforward question-and-answer format, this address should be regarded as what, here at Lawfare, we've been calling the "canonical" national security law speeches of the Obama administration.

By "canonical" we mean the major addresses on central categories of national security, particularly in counterterrorism and related fields - but speeches which have also, so far as we know, been cleared in the interagency process and reflect the views of the "US government." They can be viewed not just as the legal policy views of this administration but, like speeches delivered by Reagan administration legal adviser Abraham Sofaer and others over many decades, as statements that form part of the long-running precedents and legal views of the executive branch. Statements that are part of the body of precedent, state practice, legal understandings, and in some matters opinio juris that future administrations will draw upon and further shape. This is important in no small part because they help shape the longer run "institutional settlement" around national security policy in counterterrorism and related areas - the shared legal and policy understandings upon which future administrations of either party will rely in seeking long-term legitimacy for actions in the day-to-day.

Earlier speeches (some by officials including President Obama and senior advisors such as John Brennan, and others by the general counsels of the key national security agencies) have mostly addressed drones, targeted killing, use of force in counterterrorism, targeting of US citizens, trials, and detention. They have not up to this point addressed in any detailed way the US government's views on cyberspace and international law. (It is tempting to say "cyberwar" or "cyber-attacks," because we all know that this is a big part of the debate - but the speech is careful to say "cyberspace," presumably because the question of when some action in cyberspace is "war" or governed by the "law of war" is itself a central issue.) This speech takes up these questions of cyberspace and international law, and it will certainly be essential reading for all lawyers, journalists, policy analysts, academics and others in this area. (And ... with that general introduction, I'm going to turn it over to Paul Rosenzweig and other folks who can expertly address cyber issues.)