The patent dispute over commercial rights to CRISPR-Cas9 gene-editing technology is heating up again. After an earlier fight, inventors at the Broad Institute of MIT and Harvard were allowed to keep their CRISPR patents, and inventors at the University of California, Berkeley, were awarded their own patents. The US Patent and Trademark Office (USPTO) declared that the patents from the two groups described different inventions, and for a brief time it seemed that the two camps would coexist, which would potentially require companies using CRISPR to seek licenses from both. Then in June, the USPTO backtracked and declared that the two parties’ patents did in fact describe the same invention. A new court proceeding will determine who was the first to invent CRISPR gene editing for eukaryotes—organisms such as yeast, plants, and animals. To further complicate matters, Merck KGaA–owned MilliporeSigma, which makes life sciences tools, claims that some of its pending patent applications for CRISPR also interfere with UC Berkeley’s patents. Millipore recently petitioned the USPTO to open a new patent interference proceeding between itself and UC Berkeley, setting the stage for a three-way patent fight. At the same time, Millipore aligned with the Broad Institute to pool their CRISPR patents, allowing other groups to request a single, nonexclusive license to use CRISPR.