The University of California is fighting back in its quest to regain control over the rights to the powerful gene-editing technology known as CRISPR-Cas9.

On Tuesday, UC filed an appeal of the U.S. Patent Office’s decision last February that the patent claims to CRISPR by Feng Zhang of the Broad Institute of MIT and Harvard do not interfere with those put forth by UC Berkeley biochemist Jennifer Doudna and her European collaborator, Emmanuelle Charpentier.

Patent rights are crucial to most commercial applications of the technology.

UC asserts that its team was the true inventor of the gene editing technology. In its brief — filed with the U.S. Court of Appeals for the Federal Circuit in Washington, D.C. — it contests a dozen CRISPR-based patents held by Broad, saying that their discoveries overlapped.

“The PTAB’s (the Patent Trial and Appeal Board) ruling flies in the face of core legal principles that govern the interference-in-fact inquiry, and defies common sense,” according to the UC brief. “If uncorrected, that ruling threatens to allow Broad to arrogate to itself much of UC’s transformational invention.”

“This Court should not let such a profoundly erroneous and unjust result stand,” it asserted.

The U.S. Patent Office has sided with Broad, ruling there is “no interference in fact” — meaning that the universities’ discoveries accomplish different things. This ruling neither cancels nor refuses either parties’ claims, but leaves in place patents previously issued to the Broad Institute.

It agreed that Broad’s patents specified how CRISPR could be adapted for use in eukaryotic cells — that is, complex cells that include animal, plants, and humans — and Berkeley’s didn’t. So Broad’s patents don’t interfere with the granting of Berkeley’s patents, and should be allowed to stand, it said.

That ruling, if it stands, casts a pall over the university’s future earnings from a transformative technique devised by cell biologist Doudna — but improved upon by Zhang.

Broad’s patents could hold far greater financial value than Berkeley’s patents, because they are more useful in human medicine.

The two sides have racked up tens of millions of dollars of legal fees. But patent rights could be worth hundreds of millions.

The CRISPR gene-editing tool gives scientists near godlike power: moving genes from one living creature to another. In a mere five years, it has transformed plant and animal breeding, treatment for hereditary disease and strategies for combating infectious disease and cancer.

In the appeal, UC argues that the Patent Board used incorrect standards in assessing whether Broad’s CRISPR-Cas9 gene editing in cells was an obvious extension of UC’s core invention and the landmark June 2012 Science publication by the Doudna and Charpentier team describing that invention.

Specifically, the appeal asks the court to reverse the Patent Trial and Appeal Board’s decision that the UC application and Broad Institute patents do not interfere, or to send the interference back to the board for reconsideration of the issue using the proper criteria that have been applied in other cases. If it is established that the parties’ patent application and patents do interfere, the appeal board would decide which party is entitled to patents for use of CRISPR-Cas9 gene editing in plant and animal cells, as well as other environments.

The outcome would dictate whether whatever claims Berkeley is entitled to are limited to using the system in bacteria — or whether their claims apply to the use in cells of plants, animals and humans.

If UC wins its appeal, the court could send the issue back to the Patent Office to make another decision, say experts. If it loses, anyone who wants to use CRISPR has to license it from both UC and Broad.

In Europe, the patents are still up for grabs. Both teams have filed similar patents there and battling for patent rights.

Meanwhile, other parties are also claiming patent rights on the technology. According to the journal Nature, there are 763 patent groups that claim rights to certain aspects of CRISPR-Cas9.

“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 cell types,” said Edward Penhoet, a special adviser on CRISPR to the UC president and UC Berkeley chancellor.