Numerous friends of human embryonic stem cell research are lining up to support the National Institutes of Health (NIH) in a major court case challenging the agency’s ability to fund the research.

Tuesday, the Genetics Policy Institute (GPI), a Florida-based advocacy group and sponsor of the recent World Stem Cell Summit in Detroit, Michigan, asked the US Court of Appeals for the District of Columbia Circuit for permission to join an amicus, or friend-of-the-court, brief, filed on Monday by the University of Wisconsin. The GPI request came a day after a similar request from the Coalition for the Advancement of Medical Research (CAMR), an umbrella group of scores of patients organizations, universities, scientific societies and foundations.

Next month, the appeals court — which resides one level below the Supreme Court in the US legal system — is expected to hear oral arguments on the legality of US government funding for the research. Two adult stem cell researchers have filed suit against the government, charging that its support for the research contravenes a law banning funding for research in which embryos are destroyed. (For an overview of the case, see here.)

Also on Monday, another high-profile party weighed in: the University of California Regents filed a 6,600-word amicus brief, arguing in part that the plaintiffs, James Sherley and Theresa Deisher, should not have been granted legal standing to sue the agency. The two had said that, as adult stem cell researchers, they were being competitively injured in their attempt to win NIH funding by the agency’s support for human embryonic stem cell research. But legally, UC’s lawyers point out, it is institutions and not individual grantees who receive awards; Deisher and Sherley are therefore not “legal parties to any NIH grant” and lack the standing to sue. Even if they had standing, the brief continues,

“the harm to the public and to grantees such as UC far outweigh the speculative harm offered by plaintiffs. Plaintiffs have not shown that they have lost any grants as a result of any government policy. In contrast, the impact of even a short-lived injunction was profound and affected research scientists, and threatened active research as well as teaching programs and jeopardized jobs.”

In its 50-page brief, the University of Wisconsin argued, among other things, that Congress has clearly signaled its belief that current law allows funding of stem cell research, by doling out some $550 million for the research since 2002. In light of this, the university’s lawyers write, “appellees’ core claim that the [law] `unambiguously prohibits’ such research borders on the frivolous.”

Both the GPI and CAMR co-signed Wisconsin’s brief; however, they must now wait for the Court of Appeals’ formal permission to join as amici.

Friend-of-the-court briefs do not have the same weight as the arguments made by actual parties to a lawsuit, such as this lengthy brief filed to the Court of Appeals by the government on 14 October. But, says Amy Comstock Rick, a lawyer who is CEO of the Parkinson’s Action Network and is following the case closely: “It has been my experience that courts want to take every relevant argument and piece of information that they can under advisement. A strong argument is a strong argument, regardless of who makes it.”

So far, no amicus briefs have been filed on behalf of plaintiffs Deisher and Sherley. They have until 28 October to file with the court their own rebuttals to the written arguments the government submitted last week. By 4 November, the government needs to file a rebuttal to the rebuttal. Oral arguments should be scheduled for “the first appropriate date” after that, the court has ordered.

For full coverage of this ongoing story see Nature’s Stem Cell Injunction news special.