‘Planetary Defense’ sounds like science fiction: defending the Earth against extraterrestrial invaders, much like depicted in ‘War of the Worlds’. The reality is slightly more prosaic, but no less important in the long run: major portions of our planet and human life on it – or in the worst case all of it – may at some point in the future be at risk of annihilation at the hands of huge asteroids. While it is technology that would ultimately have to ensure timely awareness and appropriate responses when such a threat materializes, the use of such technologies also presents major legal issues which need to be solved to facilitate a successful defense of planet Earth against such asteroids.