Trace the lines of science, religion, ethics and politics and eventually they will intersect at one of the most divisive issues currently at play here: human cloning.
"Among the nonpolitical issues, it's the most contentious," Michèle Montas, spokeswoman for the United Nations General Assembly president, said recently. "They debate over and over again."
The member states of the United Nations will have another chance to express their feelings on the subject on Thursday when they consider two competing resolutions that propose bans on human cloning — and seek to establish international legal boundaries in the field of life sciences.
All the United Nations' member states agree that reproductive cloning, intended to produce a child with the same genes as its genetic parent, should be prohibited. But beyond that, consensus falls apart. The field has begun to divide sharply into two entrenched and unyielding camps.
One group, led by the United States and Costa Rica and including at least 61 other countries, has sponsored a General Assembly resolution calling for a convention that would ban all forms of human cloning — that is, banning the creation of a cloned embryo for any reason.
The second, led by Belgium and including at least 22 other countries, is pushing a counterresolution that would lead to a convention banning the creation of cloned embryos to produce another human being but permitting the use of such embryos for medical experiments.
In this process, known as therapeutic cloning and still in an experimental stage, scientists implant the nucleus of an adult donor cell into a egg whose nucleus has been removed. The eggs develop into blastocysts — four- to five-day-old embryos — from which scientists hope to develop tissues to treat human degenerative diseases.
Both resolutions would permit the unrestricted cloning of animals.
Though General Assembly conventions are nonbinding, they can be ratified by legislatures in signatory countries and, if passed with large majorities, can send a powerful message.
The cloning moderates — who, in addition to Belgium, include major powers like Britain, China and Japan — argue that in light of the widespread support for a ban on human reproductive cloning, the General Assembly should at least try to secure a universal convention on that and leave it to the individual countries to pass even stronger legislation.
"It's easier to hold the extreme full-ban position from a purely moral position but not in terms of legislation and implementation," said a diplomat from the camp proposing a moderate ban. The advocates of the full ban, the diplomat contended, "are just trying to make their point. They're not prepared to be rational."
Several of the moderate resolution's co-sponsors have already passed some form of a ban on human cloning. About 30 nations, though not the United States, have adopted national legislation or guidelines that either explicitly or implicitly prohibit reproductive cloning, according to Unesco.
Supporters of the moderate ban say that a total ban would preclude further embryonic stem cell research. An international coalition of at least 66 science organizations, including the United States National Academy of Sciences, has endorsed a ban on human reproductive cloning but has urged the United Nations and national legislatures to permit therapeutic cloning.
Therapeutic cloning "has considerable potential from a scientific perspective," the coalition said in a statement.
But co-sponsors of the total ban — which include many developing nations — say cloning is unethical and immoral, in part because it entails the destruction of the blastocyst.
The United States, in a position paper issued in August, said therapeutic cloning "would turn nascent human life into a natural resource to be mined and exploited, eroding the sense of worth and dignity of the individual." It called the destruction of cloned human embryos "a morally abhorrent prospect."
During a General Assembly debate in October, Birhanemeskel Abebe, a top official from the Ethiopian mission here, urged a total ban, saying: "Every human being has intrinsic dignity and worth from conception to natural death. Embryo destruction for research purpose fatally disrespects human life." The process, he said, "upsets the social order by confounding the meaning of parenthood and confusing the identity and kinship relations of any cloned child."
A State Department official explained that the American stance is a reflection of President Bush's strongly held views. The Bush administration's support for a total ban stands in opposition to the majority support among American scientists for the right to conduct therapeutic coning.
"I think it's something the administration passionately believes in and some of its supporters do," the State Department official said, adding, "That's not to say to you that people from some of the very conservative religious groups haven't made their views known."
A partial ban, opponents have argued, would leave open the door to abuses, with the emergence of a black market in embryos provided by impoverished women. "Stockpiles of cloned human embryos could be produced, bought and sold without anyone knowing it," the United States mission said in its position paper. "The tightest regulations and strict policing would not prevent or detect the birth of cloned babies."
Finally, the supporters of a total ban say that the scientific ends sought by the scientists using therapeutic cloning may be achieved through other techniques, including the use of stem cells extracted from adults, which do not require the creation of embryos.
This assertion, though, is the subject of intense debate among scientists, said Orio Ikebe, an official in the bioethics section of Unesco.
Belgium's ambassador here, Jean de Ruyt, said in an interview last week that in the absence of scientific certainty, the General Assembly "should leave the door open" to further investigation.
Indeed, that appears to be a likely outcome of the debate this week. The issue is scheduled for consideration on Thursday, but several diplomats say that instead of allowing the resolutions to come to a vote, a bloc of undecided nations, led by the Islamic nations, may push to defer the issue for two years.
The American ambassador to the United Nations, John D. Negroponte, urged the supporters of a total ban to vote against a delay, saying in a letter on Oct. 30 that "there is a need to act now to confront the emerging threat of human cloning."
But Mr. de Ruyt said that a delay might be "the wisest" strategy now.
"It's not much use to have a divided world on this," he said. Unless the United Nations can send a clear and unequivocal message about the permissibility of cloning, he said, scientists will continue to pursue human cloning of all sorts wherever it is still permitted.
"There will be anarchy," he warned.