This paper examines the copyright challenges surrounding the use of map data for disaster prevention and explores how hyper-layering technology offers a viable solution. Based on discussions at the 2024 Digital Archive Society (DA) Session, we analyze how hyper-layering—linking to external data without duplication—avoids infringing upon reproduction or transmission rights under Japanese copyright law. Attorney Kensaku Fukui affirmed its legality, while Professor Kimiro Meguro and others emphasized its practical significance. This paper not only examines this legal arrangement but also looks at the future use of map data for disaster prevention from the viewpoint of disaster prevention and public interest through ethical considerations.