Human reproductive cloning remains universally condemned, primarily for the psychological, social, and physiological risks associated with cloning. A cloned embryo intended for implantation into a womb requires thorough molecular testing to fully determine whether an embryo is healthy and whether the cloning process is complete. In addition, as demonstrated by 100 failed attempts to generate a cloned macaque in 2007, a viable pregnancy is not guaranteed. Because the risks associated with reproductive cloning in humans introduce a very high likelihood of loss of life, the process is considered unethical. There are other philosophical issues that also have been raised concerning the nature of reproduction and human identity that reproductive cloning might violate. Concerns about eugenics, the once popular notion that the human species could be improved through the selection of individuals possessing desired traits, also have surfaced, since cloning could be used to breed “better” humans, thus violating principles of human dignity, freedom, and equality.

There also exists controversy over the ethics of therapeutic and research cloning. Some individuals and groups have an objection to therapeutic cloning, because it is considered the manufacture and destruction of a human life, even though that life has not developed past the embryonic stage. Those who are opposed to therapeutic cloning believe that the technique supports and encourages acceptance of the idea that human life can be created and expended for any purpose. However, those who support therapeutic cloning believe that there is a moral imperative to heal the sick and to seek greater scientific knowledge. Many of these supporters believe that therapeutic and research cloning should be not only allowed but also publicly funded, similar to other types of disease and therapeutics research. Most supporters also argue that the embryo demands special moral consideration, requiring regulation and oversight by funding agencies. In addition, it is important to many philosophers and policy makers that women and couples not be exploited for the purpose of obtaining their embryos or eggs.

There are laws and international conventions that attempt to uphold certain ethical principles and regulations concerning cloning. In 2005 the United Nations passed a nonbinding Declaration on Human Cloning that calls upon member states “to adopt all measures necessary to prohibit all forms of human cloning inasmuch as they are incompatible with human dignity and the protection of human life.” This does provide leeway for member countries to pursue therapeutic cloning. The United Kingdom, through its Human Fertilisation and Embryology Authority, issues licenses for creating human embryonic stem cells through nuclear transfer. These licenses ensure that human embryos are cloned for legitimate therapeutic and research purposes aimed at obtaining scientific knowledge about disease and human development. The licenses require the destruction of embryos by the 14th day of development, since this is when embryos begin to develop the primitive streak, the first indicator of an organism’s nervous system. The United States federal government has not passed any laws regarding human cloning due to disagreement within the legislative branch about whether to ban all cloning or to ban only reproductive cloning. The Dickey-Wicker amendment, attached to U.S. appropriations bills since 1995, has prevented the use of federal dollars to fund the harm or destruction of human embryos for research. It is presumed that nuclear transfer and any other form of cloning is subject to this restriction.