In 1991, the United Kingdom established the Human Fertilisation and Embryology Authority (HFEA) as a response to technologies that used human embryos. The HFEA is a regulatory power of the Health and Social Services Department in London, UK, that oversees the implementation of reproductive technologies and the use of embryos in research within the United Kingdom. It establishes protocols by which researchers may use human embryos, develops legislation on how human embryos are stored and used, monitors human embryological research and artificial fertilization procedures, and prosecutes those who violate terms of embryo use. The HFEA collects, monitors, and distributes data related to human embryology and embryological research. The HFEA also records international studies involving human embryos and fertilization, hosts ethical debates, and shares collected information with the public and scientific communities.

To educate its citizens about research into chimeras made from human and non-human animal cells, the United Kingdom's Human Fertilisation Embryology Authority published the consultation piece Hybrids and Chimeras: A Consultation on the Ethical and Social Implications of Creating Human/Animal Embryos in Research, in 2007. The document provided scientific and legal background, described ethical and social issues associated with research using part-human part-animal embryos, supplied a questionnaire for citizens to return to the HFEA with their opinions, and offered a list of resources for further reading to stimulate public debate. The strategy of surveying the public provided a template for developing further policy in the United Kingdom and other countries, as well as for educating citizens on embryological research.

In 2007, the Human Fertilisation and Embryology Authority in London, UK, published Hybrids and Chimeras: A Report on the Findings of the Consultation, which summarized a public debate about research on, and suggested policy for, human animal chimeras. The HFEA formulated the report after conducting a series of surveys and debates from earlier in 2007. The HFEA issued a statement in September 2007, followed by an official report published on 1 October 2007. Their report on human-animal chimeras set a worldwide precedent for discussions of the ethical use of those embryos in labs. The HFEA's report led the UK government to pass legislature about the use of human-animal cytoplasmic hybrid embryos for research in the UK.

The Human Fertilisation and Embryology Act 1990 established the legal framework that governs infertility treatment, medical services ancillary to infertility treatment such as embryo storage, and all human embryological research performed in the UK. The law also defines a legal concept of the parent of a child conceived with assisted reproductive technologies. Section Five of the Act establishes the Human Fertilisation and Embryology Authority, the first of its kind in the world, to enforce and regulate the responsibilities that scientists, doctors, and prospective parents have towards embryos and to each other. Upon introducing the act to the House of Commons, the Secretary of State for Health of the time, Kenneth Clarke, said the bill was in his opinion the most important piece of legislation considered by the government in two decades.

Since the 1950s, scientists have developed interspecies blastocysts in laboratory settings, but not until the 1990s did proposals emerge to engineer interspecies blastocysts that contained human genetic or cellular material. Even if these embryos were not permitted to mature to fetal stages, their ethical and political status became debated within nations attempting to use them for research. To study cell differentiation and embryonic development and causes of human diseases, interspecies-somatic-cell-nuclear-transfer -derived (iSCNT) humanesque blastocysts provided opportunities for research and therapy development. Such a technology also involved ethical debates.