Open-source licenses are infrastructure that collaborative communities in-habit. These licenses don’t just define the legal terms under which members (and outsiders) can use and build on the contributions of others. They also reflect a community’s consensus on the reciprocal obligations that define it as a community. A license is a statement of values, in legally executable form, adapted for daily use. As such, a license must be designed, much as the software and hardware that open-source developers create. Sometimes an existing license is fit to purpose and can be adopted without extensive discussion. However, often the technical or social needs of a community do not precisely map onto existing licenses, or the community itself is divided about the norms a license should enforce. In these cases of breakdown, the community itself must debate and design its license, using the same social processes it uses to debate and design the other infrastructure it relies on, and the final goods it creates. In this paper, Madiha Zahrah Choksi and James Grimmelmann analyze four case studies of controversy over license design in open-source software and hardware ecosystems.