The US Supreme Court today ended an effort to shut down government support of human embryonic stem cell research, refusing to hear a case that challenged the legality of funding for the work by the National Institutes of Health (NIH).

The high court’s refusal to consider an appeal in the case of Sherley v. Sebelius ends a more than 3-year-old effort by the plaintiffs, two adult stem cell researchers, to stop NIH backing of the work, which holds the promise of treatments for a variety of diseases, but which depends upon the destruction of days-old human embryos. As is its typical practice, the court did not give its reasons for declining the case.

Embryonic stem cell researchers were jubilant. “We couldn't be happier that this frivolous, but at the same time potentially devastating distraction is behind us,” says Douglas Melton, the co-scientific director of the Harvard Stem Cell Institute in Cambridge, Massachusetts. But the lead plaintiff on the case, James Sherley of the Boston Biomedical Research Institute in Watertown, Massachusetts, said that the case's end would not end his efforts “to emancipate human embryos from research slavery sponsored by the NIH.”

It was in August, 2009, that Sherley and Theresa Deisher, the chief executive officer of AVM Biotechnology in Seattle, Washington, sued Health and Human Services Secretary Kathleen Sebelius and NIH director Francis Collins. The lawsuit came several months after the NIH published guidelines implementing an executive order by President Barack Obama, which liberalized the stem cell policy of his predecessor, George W. Bush, and led to scores of new human embryonic stem cell lines being available to NIH-funded researchers. Under the guidelines, the lines must be derived, with informed donor consent, from leftover embryos at fertility clinics that would have been thrown away anyway. The NIH does not fund the derivation of the lines, but only the subsequent research.

When the case came before Judge Royce Lamberth of the US District Court for the District of Columbia in August, 2010, he shocked the research community by issuing an injunction that shut down all NIH-funded experiments for 17 days, until a higher appeals court stayed the injunction while the case moved through the courts.

A three-judge panel of that higher court, the US Court of Appeals for the District of Columbia Circuit, ruled against the plaintiffs in August, 2012. It said that NIH had reasonably interpreted the Dickey Wicker amendment, the 17-year-old law at issue in the case. The law says that NIH funds may not be used in research in which an embryo is “destroyed” or “discarded.”  The court found the law’s wording ambiguous enough to allow NIH to fund research on the cell lines, if not their derivation.

Sherley and Deisher then appealed to the Supreme Court, the court of last resort. While the case may be over, Deisher says that the lawsuit nonetheless accomplished one of its goals: Some scientists and clinicians have focused their efforts on working with adult stem cells.

But the definitive end of the case was celebrated by supporters of the research, who say it could lead to therapies for Parkinson’s Disease, diabetes and other ailments. “What a great day for science,” says Amy Comstock Rick, the president of the Coalition for the Advancement of Medical Research in Washington, DC, an umbrella group of organizations that advocate for the research. Collins pronounced himself  “very pleased”.

Under Obama, the NIH has made 195 stem cell lines available for use to researchers; under Bush, the number was around 20. George Daley, an NIH-supported stem cell researcher at Children’s Hospital in Boston, Massachusetts, says he is relieved. “The ruling erases the nagging worry that existing funding could be cut off at any time.” Still, he says, the threat alone achieved some of its intended effect — to instill enough uncertainty to keep some researchers from entering the field.

This article is reproduced with permission from the magazine Nature. The article was first published on January 7, 2013.