A US appeals court has revived the patent dispute over CRISPR–Cas9 gene-editing technology between the University of California/University of Vienna team and the Broad Institute. The court found that the Patent Trial and Appeal Board erred by awarding patents based on who first demonstrated CRISPR efficacy rather than who first invented it. This ruling grants Jennifer Doudna and Emmanuelle Charpentier’s groups another opportunity to claim priority for CRISPR–Cas9 invention rights in the United States, potentially reshaping control over foundational gene-editing intellectual property.