The University of California, Berkeley is appealing a ruling that the disputed patents on the gene-editing tool CRISPR belong to the Broad Institute of MIT and Harvard. This means the heated battle over who owns one of the most revolutionary biotech inventions of our time will likely continue for months or even years from now.

Last February, the US Patent Trial and Appeal Board ruled that the patents owned by the Broad are different enough from the ones UC Berkeley applied for that the Broad patents stand. The ruling suggested that the work done by Jennifer Doudna of UC Berkeley and her colleagues on CRISPR wasn’t so groundbreaking as to make any other advance obvious. 

UC Berkeley believes the patents overlap, and is appealing that decision in the US Court of Appeals for the Federal Circuit in Washington, DC. The Broad, for its part, seems confident the appeal will go nowhere. “Given that the facts have not changed, we expect the outcome will once again be the same,” Lee McGuire, chief communications officer of the Broad, said in a statement. “We are confident the Federal Circuit will affirm the PTAB decision and recognize the contribution of the Broad, MIT, and Harvard in developing this transformative technology.”

CRISPR-Cas9 is a technique that allows scientists to cut DNA, inserting or reordering bits of genetic code with remarkable precision and results. The gene-editing tool has already been used to create mosquitoes that don’t transmit malaria, unusually muscular beagles, and miniature pet pigs. In the future, CRISPR could change the way we fight cancer and help treat debilitating genetic diseases like sickle cell anemia and cystic fibrosis.

Its potential is limitless, and so is the amount of money and fame that whoever owns the intellectual property of the technology would get. The CRISPR patents are estimated to be worth billions of dollars. And that’s why the legal battle has been so heated. The two parties involved in the dispute — the University of California, Berkeley and microbiologist Emmanuelle Charpentier on one side, and the Broad Institute and MIT on the other — have been fighting for years now, spending millions of dollars on the case.

It all began in 2012, when Doudna and others, including Charpentier, published a seminal Science paper on CRISPR. In this paper, Doudna showed that the gene-editing technology can be used to cut DNA in a test tube at targeted sites. Later, Doudna filed a patent application for CRISPR.

Then in 2013, in another Science paper, MIT bioengineer Feng Zhang and his team reported developing a CRISPR system that edited genomes in eukaryotic cells — the cells of animals and people. When Zhang filed his own patent application, he applied for the Patent and Trademark Office (PTO) to “fast track” its patent review process. The result was that although UC Berkeley filed first, the PTO actually awarded the patent to the Broad and MIT in April 2014. (The Broad and MIT were later awarded a bunch of other CRISPR patents.) So UC Berkeley asked for a so-called “interference proceeding” — an official reassessment to determine who was the first to invent the gene-editing tool CRISPR-Cas9.

The proceeding was granted in January of last year, and in December 2016 the two parties challenged each other at a heated hearing in Alexandria, Virginia. At the hearing, UC Berkeley’s attorneys argued that after the publication of Doudna’s 2012 CRISPR paper, anyone could have applied the technique to edit eukaryotic cells. In other words, Zhang’s use of CRISPR was an “obvious” development of the technology and his patents are without merit, UC Berkeley says. The Broad’s attorney fiercely opposed that argument, claiming that Zhang’s use of CRISPR to edit complex organisms like human cells was a huge inventive leap, so he deserves the patents.

In February, the PTAB decided to terminate the interference, and now, UC Berkeley wants to reinstate it. "Ultimately, we expect to establish definitively that the team led by Jennifer Doudna and Emmanuelle Charpentier was the first to engineer CRISPR-Cas9 for use in all types of environments, including in non-cellular settings and within plant, animal and even human cells," Edward Penhoet, a special adviser on CRISPR to the University of California, said in a statement.

Last month, the European Patent Office announced that it would award the University of California with a patent for the use of CRISPR in both prokaryotic and eukaryotic systems — a decision that went against the ruling by the US patent office.