Carbon dioxide (CO2) emissions are one of the main causes of climate warming. A reduction of global CO2 emissions is not forseeable in the near future. One option to reduce CO2 in the atmosphere is the long-term storage in suitable formations under ground (so called Carbon Capture and Storage). However, technical feasibility as well as legal Regulation pose still difficulties. The Dissertation explains the Nexus between CO2 and climate change as well as the functioning of Long-term storage. Further, the legal questions concerning CCS are treated. The Focus is on public international law questions (territorial sovereignty, international legal protection of the sea, international climate protection) and European Union law (climate protection law, Primary legal requirements, bindings to public international law, adoption of Directive 2009/31/EC) including the Transposition of Directive 2009/31/EC into national law in Austria and Germany. The analyses demonstrates that public international law does not prohibit CCS within the territorial boundaries of a State. In general, public international law does neither contain a categorical prohibition nor obligation to use CCS. A complete prohibition would contradict the Spirit of the Kyoto protocol. Directive 2009/31/EC is part of the EU climate protection package and aims at ensuring CO2 reduction. Member States enjoy a wide discretion when implementing the directive. This discretion is, however, reduced when only a combination of all measures mentioned in the Kyoto Protocol may ensure the envisaged reduction. Substantively, the directive governs the different phases of CCS Projects.