Species reintroductions, an increasingly used measure in conservation, may be imposed, hindered, or conditioned by law. The European bison (Bison bonasus), once extinct in the wild, now lives in several free-ranging populations all stemming from reintroductions. Reintroduction of European bison to Sweden has been proposed and advocated. Zooarchaeological findings indicate that wild European bison existed in Sweden 11,200-9,500 years before present. Here we address and apply the relevant legal prerequisites for a reintroduction of European bison to Sweden. Applying international, European Union, and national Swedish law, we first show that there is no strict obligation for Sweden to reintroduce European bison. The responsible authority has considerable discretion in whether to allow a reintroduction of European bison. Rules on species protection, site protection, animal health, and animal welfare set conditions for how a reintroduction process should be implemented. Unclear legal rules on compensation and civil liability for damages caused by European bison create uncertainties about financial risks. Finally, the European bison is a protected species under the EU Habitats Directive, which further limits management options after reintroduction. Our assessment shows how law influences the feasibility of a reintroduction of a protected animal species to an EU Member State.