Our aims are to (1) set forth a multiprinciple system for selecting among clinical trials competing for limited space in an immunotherapy production facility that supplies products under investigation by scientific investigators; (2) defend this system by appealing to justice principles; and (3) illustrate our proposal by showing how it might be implemented. Our overarching aim is to assist manufacturers of immunotherapeutic products and other potentially breakthrough experimental therapies with the ethical task of prioritizing requests from scientific investigators when production capacity is limited.