Climate adaptation of vital societal functions – a deep dive into the legal issues The climate is changing. This can lead to more frequent extreme weather events which can cause major damages in cities. Especially in larger cities, the climate related damages can go far beyond individual homeowners, as e.g. flooding can impair important societal functions. Today, many cities face the need to implement effective climate adaptation measures. But it is neither possible nor economically justifiable to secure all infrastructure in our cities against all types of climate-related risks. Cities need to prioritize their measures. They may be faced with, for example, the choice of investing in extensive and costly redevelopments or take smaller measures to only protect vital societal functions. Careful consideration of other interests, such as accessibility, is also required. There are organizational, technical, and legal challenges. The roles and responsibilities for various private and public entities, regarding climate adaptation measures, are not entirely clear. In the project “Multifunctional urban climate adaptation in collaboration” (Multifunktionell urban klimatanpassning i samverkan, MuKlis), financed by Vinnova, we explore the conditions for implementing efficient and sustainable climate adaptation of the built urban environment. The focus is on reducing vulnerability in case of cloudburst and heat waves with measures that also create other social, economic, and environmental benefits. In the project, we also explore legal challenges and possibilities for climate adaptation of vital societal functions and critical infrastructure, with a specific focus on the following questions: • If it is legally possible for a public or private actor to protect vital societal functions and critical infrastructure, even if it means an impairment for other actors in the area. • If it is legally possible for local, regional, or national government to demand that a public or private actor protect its vital societal functions and critical infrastructure. • If it is legally possible for an actor with vital societal functions to demand that another actor shall climate-proof for the benefit of its own vital societal functions and critical infrastructure. • If there are special provisions that can be applied if the vital societal functions or critical infrastructure are covered by the scope of the Protective Security Act (i.e. when the vital societal functions or critical infrastructure are also considered as security-sensitive activities).