The dispute over who was first to invent CRISPR-Cas9 genome editing in eukaryotic cells has resumed with the US Patent and Trademark Office (USPTO) declaring an interference between the University of California (UC) and the Broad Institute of MIT and Harvard. The patent office’s decision came in June, just nine months after a federal court upheld a no-interference judgement that gave the Broad control of key CRISPR intellectual property. The new interference case involves 13 of the Broad’s 15 patents and one application, and 10 patent applications submitted by UC Berkeley and partners. It is a signal that the USPTO has determined that one or more of Berkeley’s patent applications are substantially the same as previously issued Broad patents. Since the federal court’s September 2018 ruling, which declared no interference and appeared to be a win for Broad and Harvard, UC Berkeley has been granted six CRISPR patents in the United States. These include a foundational patent that covers systems and methods for the use of single-molecule guide RNAs combined with the Cas9 protein to modify target DNA in any setting, including in vitro and in cells. In addition, in May the Broad Institute had its third European CRISPR patent revoked by the European Patent Office for lacking in inventive step. UC Berkeley has maintained a dominant CRISPR patent position in Europe, while the Broad has held the upper hand in the United States. However, the newly filed interference could upend the current balance of power. “The initiation of this interference proceeding highlights that previous decisions involving the Broad did not determine who was the first to invent this technology, and it lays out a pathway for resolving this important issue,” said Eldora Ellison, lead patent strategist on CRISPR matters for UC Berkeley.