Generative AI gives rise to many questions about how to license very large amounts of content efficiently where the need arises. One of the types of licensing schemes that has been discussed is “opt-out,” in which online services use copyrighted material unless rightsholders tell them not to (e.g., YouTube), as opposed to “opt-in,” in which online services require permissions from rightsholders to use their content (e.g., Spotify). This panel discusses deliberations and controversies over opt-out schemes for AI training that have taken place in the UK and EU as well as in the US, and some of the technical challenges in implementing workable opt-out schemes.