Debates continue to surround the system in the United States for allocating transplantable cadaveric organs, due in large part to the scarcity of such organs in relation to the number of individuals waiting to undergo transplantation. Candidates awaiting transplantation gain access to cadaveric organs by being placed by individual transplant programs on the national list of the Organ Procurement and Transplantation Network (OPTN), overseen by the United Network for Organ Sharing (UNOS). In recent years, the UNOS board has visited (and revisited) the issue of multiple listing, that is, allowing one candidate to be registered on the waiting lists of two or more transplant programs, and has continued to permit multiple listing.