Nuclear fusion offers the chance to satisfy the world's hunger for energy as a practically endlessly available, emission-free and safe source of energy and thus to make a central contribution to combating the climate crisis. While scientific research continues unabated and the commercialisation of the technology draws ever closer, there has been a lack of comprehensive discussion of the legal framework of nuclear fusion. This work deals intensively with the legal framework of international nuclear law and its four classical pillars - safety, security, safeguards and civil liability for nuclear accidents - in relation to nuclear fusion.