A quarter of a century ago, biologists met at a conference center in Pacific Grove, Calif., and took an unusual step. They agreed to temporarily halt experiments in the fledgling field of genetic engineering until the scientists could meet public concerns over the safety their efforts.
Twenty-seven years later, the National Academy of Science is recommending a more dramatic step that would temporarily close another arena of biotechnology in the United States. An academy panel has proposed unanimously that lawmakers outlaw cloning humans - at least for a limited period of time.
Current approaches to cloning are "dangerous and likely to fail," the panel concludes, threatening the foetus, the child, and the mother.
The panel said its report was not designed to tackle the ethical controversies surrounding cloning. But the call for a temporary ban on reproductive cloning could still factor prominently in that ethical debate - and hence in federal and state legislation.
Such a ban could strengthen the position of biomedical scientists as they argue for the freedom to clone human embryos for medical research.
The National Academy of Sciences (NAS) strongly supports the use of cloned embryos to produce stem cells for research - a position the panel reaffirmed. Meanwhile few medical scientists see any value to cloning humans, but some private groups are interested in pressing ahead on the controversial practice.
The report recommends that the scientific and medical concerns surrounding human cloning should be reviewed within five years of the ban's enactment.
The panel said the ban should be lifted only if cloning procedures are found safe and effective and if the public appears willing to reconsider it.
As early as next month, the Senate is expected to open debates over bills to ban human cloning. The House passed similar legislation last July. In addition, 15 states face their own legislative battles this year on the issue.
The report also comes at a time when the Bush administration is seeking guidance on the ethics of cloning.
The president's new Council on Bioethics met last week to discuss the issue, which touches deeply held convictions that include the value of the individual and family, the nature of identity, and the dangers of technological hubris.
Indeed, the NAS panel for the most part avoided tackling ethics issues, deferring to groups such as the Council on Bioethics.
"It was our charge to investigate the medical and scientific aspects of this subject," says Irving Weissman, a Stanford University biomedical researcher who headed the NAS panel. On ethics, "we defer to groups like the President's Council on Bioethics. Science needs to be a participant in these discussions, but not the determining force."
While few biomedical scientists see compelling reasons to clone humans, many believe stem cells from cloned embryos hold great promise as tools for studying human diseases and, eventually, for regenerating damaged or diseased tissue.
But to groups such as the National Right to Life Committee, whose members hold that human life begins at conception, cloning embryos for stem-cell research is tantamount to turning laboratories into factories that sacrifice countless unborn on the altar of medical research.
The House-passed anticloning bill and one pending Senate version would ban cloning of embryos for stem-cell research purposes, as well as for implantation in prospective mothers.
In recommending a legally binding ban on cloning humans, "there clearly was unease" among panel members over the precedent they might set, says Mark Siegler, director of the MacLean Center for Clinical Medical Ethics at the University of Chicago and a member of the NAS panel. "But the issue is so profound for the scientific community and for society."
Moreover, he says it became clear during a workshop last summer that some private groups planned to move ahead on cloning of humans.