Within days of President Bush's announcement on the funding of stem-cell research, the first of many likely legal battles over stem-cell technology rights was underway.

On 13 August, just four days after Bush's statement, the Wisconsin Alumni Research Foundation (WARF) filed a lawsuit in an effort to keep its private partner Geron of Menlo Park, California, from taking too large a piece of the commercial pie. WARF holds the patent on human embryonic stem cells in the United States.

But shortly afterwards, both parties issued a statement saying that, despite the lawsuit, they were still negotiating with each other on the patent, and that they expect to resolve the matter "in the near future".

Geron sponsored the research of James Thomson at the University of Wisconsin in Madison, who in 1998 derived the first human embryonic stem cells. In return, WARF, through which many University of Wisconsin inventions are patented, granted Geron limited rights to the technology.

Under the agreement, Geron has the right to commercialize any applications involving six of the more than 200 cell types in the human body — liver, muscle, nerve, bone, blood and the insulin-producing pancreatic islet cells.

At the end of July, Geron exercised an option in the contract to claim an additional 12 cell types. But WARF argues in the suit that not only had the option expired a week earlier, but that it could also be denied at WARF's discretion.

Although any cell type can be derived from embryonic stem cells, some are more likely to yield commercially viable therapeutics than others. WARF is seeking to keep some of the more promising cell types available to other researchers.

"We couldn't figure out a way to resolve this without a third party," says WARF spokesman Andrew Cohn. He says WARF and Geron have been negotiating the option for seven months.