The Swiss Federal Council (Bundesrat) ruled in March to ban xenotransplantation from animals to humans, except in clinical research. The move is intended to appease green lobbyists, who have been calling for a moratorium. However, the partial ban permits what is technically not yet possible, thus allowing research to continue: Clinical trials of whole-organ xenotransplantation are allowed, although researchers in Switzerland think this will not be technically possible for at least another 10 years. The transplantation of tissue and cells as an individual treatment is allowed, providing there is no risk of infection for the population and there is proof of therapeutic benefit. Switzerland is the first country in the world to explicitly prohibit xenotransplantation; the partial ban will be effective until 2002, when a full law regulating xenotransplantation is passed.