In the three years since President Bush tried to balance the progress of science with the belief that to destroy a human embryo was wrong, research in the field has continued and the ethical questions around it have intensified. U.S. scientists, standard bearers in demanding that ethics accompany their work, have missed guiding some of the international debate because of the limits imposed by the administration.

The clearest example of this emerged last winter when geneticists in South Korea demonstrated for the first time that therapeutic cloning in humans can be achieved. The researchers there grew 30 cloned embryos to about 100 cells, the farthest scientists had gotten to date.

While the purpose of the cloning was for therapy – treatment of perhaps Alzheimer’s disease, Parkinson’s, ALS, cancer or spinal cord damage – the work makes it easier for unscrupulous scientists to advance attempts to clone a baby. Most nations already ban and support a global ban on this sort of research, but attempts at the United Nations to impose one have failed, in part because nations, including the United States, also want a ban on therapeutic cloning.

When the president explained in August 2001 how publicly funding research would continue in the United States, his administration said scientists could continue to use between 60 and 70 extant embryonic stem-cell lines and that $100 million in funding would be available annually to conduct research. Scientists at the time doubted the quality of some of these lines and, indeed, it turns out that fewer than 20 are available for research. The budget from the National Institutes of Health for this work is about $25 million.

The presidential campaign of Sen. John Kerry has seized on this to suggest that the Bush administration is anti-science, which isn’t true. But it is fair to say that the amount of work being done in this area is less than what the administration anticipated three years ago and that other nations are making advances without the kind of international agreement that could raise ethical standards generally. The Kerry campaign is well aware that a significant majority of the public support therapeutic cloning, as do a dozen Republican members of the U.S. Senate.

That makes reconsideration by President Bush more difficult. But at the very least the president should announce that he will review practices so far before the planned September 2005 U.N. meeting on the issue. Embryonic stem-cell research is difficult science and it’s difficult politics. Just as one scientific breakthrough builds on previous work, however, the president’s next set of policies on stem-cell research should advance the limits established three years ago.