Research using chimpanzees is under closer scrutiny than usual in the United States, with the Institute of Medicine scheduled to report next month on whether government funding for the work continues to be scientifically justified. So it is, to put it mildly, an unfortunate time for questions to be raised about a key research centre's ability and willingness to follow a 16-year-old moratorium on chimpanzee breeding. It is also a sensitive time for the National Institutes of Health (NIH) in Bethesda, Maryland — the agency that funds the research on behalf of the US taxpayer — to be reluctant to answer key questions about its enforcement of the moratorium at the New Iberia Research Center (NIRC), near Lafayette in Louisiana.

The centre houses 348 chimps, of which 117 are NIH-owned, and receives a steady stream of public funds for their upkeep — around US$1 million a year. The NIRC has also received more than $6 million since 2002 to supply very young chimps to the NIH's National Institute of Allergy and Infectious Diseases for hepatitis C studies — a project that the institute calls “essential” for progress towards a vaccine.

The moratorium is designed to cap upkeep costs and prevent the taxpayer from picking up the bill for a lifetime of care for chimps born to publicly owned animals. But as Nature reports this week (see page 453), the NIRC has been forced to admit to the births of 137 infant chimps to NIH-owned animals between 2000 and 2009 — revealed by the Humane Society of the United States in Washington DC using state and federal laws on freedom of information.

The US public supports biomedical research in good faith and deserves better.

In defence of the NIRC, its director Thomas Rowell points to a clause in the written agreement between the NIH and the NIRC, which stipulates that infant chimps born during the funding period become the property of the centre, not of the NIH. The taxpayer is thus not responsible, he argues, and a valuable biomedical resource is maintained.

Yet surely the provision was written to protect the NIH from financial responsibility for infant chimps that are born occasionally and accidentally — not as the go-ahead for a breeding programme conducted with a nod and a wink? After all, the agreement also stipulates that “as a condition of this award, a moratorium on breeding activities ... will remain in effect”.

The moratorium was introduced by the NIH in 1995 for fiscal reasons; it costs at least $300,000 to support a single chimp for its lifetime. But today the moratorium carries increasing moral weight, as public opposition to chimp research has grown and the United States has become one of only two nations that supports such work.

Almost as disturbing as the NIRC's stance — which seems cavalier at best, and openly defiant of the moratorium at worst — is the silence with which the NIH has greeted repeated enquiries from Nature and others. It is not as if the agency has been caught off-guard; it has known that the issue was simmering since the summer of 2010, when the Humane Society took evidence of the 137 chimp births to the US Senate committee that funds the NIH. In a written report, the committee asked the NIH to look into the allegation that the NIRC was openly breaching the moratorium. The NIH, responding in writing, minimized the findings, saying that only 28 births to NIH-owned animals had been recorded at the centre since 1995, and arguing that the NIRC “is in compliance with the conditions of the moratorium” because it assumed ownership of the animals.

The agency has since refused to discuss its responses and has not answered a petition from the Humane Society that was filed eight months ago with the Department of Health and Human Services, the NIH's parent agency, asking that the centre's NIH funding be revoked.

The US public, which supports biomedical research in good faith and is increasingly concerned about the welfare of research animals in general, and chimps in particular, deserves better. The NIH should fully explain how it enforces the breeding moratorium at the NIRC. It should say how it is possible that 137 births in a decade were somehow permitted. And it should address publicly how one of its institutes can in good conscience pay for and use a steady supply of infant chimps born in apparent breach of the moratorium.

Until officials are fully open with the public and demonstrate convincingly that the research centres they help to fund are both competent and compliant with the rules — and that, when they are not, the proper sanctions will ensue — US chimpanzee research risks losing public support entirely, and with good reason.