A fierce and unprecedented patent battle between two educational institutions might be nearing a close, after a US appeals court issued a decisive ruling on the rights to CRISPR–Cas9 gene editing.

On 10 September, the US Court of Appeals for the Federal Circuit awarded the pivotal intellectual property to the Broad Institute of MIT and Harvard in Cambridge, Massachusetts, upholding a previous decision by the US Patent and Trademark Office. The decision spells defeat for a team of inventors at the University of California, Berkeley (UC), led by molecular biologist Jennifer Doudna.

The “Board’s underlying factual findings are supported by substantial evidence and the Board did not err”, Judge Kimberly Moore wrote in the latest decision. “We have considered UC’s remaining arguments and find them unpersuasive.”

The dispute centred on the rights to commercialize products developed by using the CRISPR–Cas9 system to make targeted changes to the genomes of eukaryotes — a group of organisms that includes plant and animals. Although many patents have been filed describing various aspects of CRISPR–Cas9 gene editing, the Broad Institute and UC patent applications were considered to be particularly important because they covered such a wide swath of potential CRISPR-Cas9 products﻿.

Investors have watched the case closely, even as they poured millions into companies that aim to develop medicines and crops using CRISPR–Cas9. The zeal with which both institutions defended their patents was unusual, says Jacob Sherkow, a legal scholar at New York Law School in New York City. Normally, he says, such institutions would settle out of court before the case ﻿reached this point.

“This has been one of the single most heated disputes between two educational institutions over inventorship,” says Sherkow. “It’s hard for me to imagine the same thing happening again.”

UC could now appeal the decision to the US Supreme Court, but it is unclear whether the court would agree to hear the case.

Since researchers filed the original CRISPR-Cas9 patents, the fast-paced field of CRISPR biology has moved on. Researchers have since discovered ﻿new enzymes to replace Cas9, and modified the CRISPR-Cas9 system to manipulate the genome in many ways, from editing individual DNA letters to activating gene expression.

Although CRISPR-Cas9 is still often the preferred CRISPR variety for researchers in both industry and academia, other systems may grow in popularity as scientists gain more experience with them. “This is still an incredibly important case for the present,” says Sherkow. “But it may not be an incredibly important case for the future.”