Stem cell laws and policy in the United States
In May 2005, the House of Representatives voted 238-194 to loosen the limitations on federally funded embryonic stem-cell research — by allowing government-funded research on surplus frozen embryos from in vitro fertilization clinics to be used for stem cell research with the permission of donors — despite Bush's promise to veto if passed.  On July 29, 2005, Senate Majority Leader William H. Frist (R-TN), announced that he too favored loosening restrictions on federal funding of embryonic stem cell research. On July 18, 2006, the Senate passed three different bills concerning stem cell research. The Senate passed the first bill, 63-37, which would have made it legal for the Federal government to spend Federal money on embryonic stem cell research that uses embryos left over from "in vitro" fertilization procedures. On July 19, 2006 President Bush vetoed this bill. The second bill makes it illegal to create, grow, and abort fetuses for research purposes. The third bill would encourage research that would isolate pluripotent, i.e., embryonic-like, stem cells without the destruction of human embryos.
Mitochondrial replacement therapy
In the United Kingdom, following animal experiments and the recommendations of a government commissioned expert committee, the Human Fertilisation and Embryology (Research Purposes) Regulations were passed in 2001 regulating and allowing research into human embryos. In 2004, the Newcastle University applied for a licence to develop pronuclear transfer to avoid the transmission of mitochondrial diseases, and was granted the license in 2005. Following further research by Newcastle and the Wellcome Trust, scientific review, public consultations, and debate, the UK government recommended that mitochondrial donation be legalized in 2013. In 2015 parliament passed the Human Fertilisation and Embryology (Mitochondrial Donation) Regulations, which came into force on 29 October 2015, making human mitochondrial donation legal in the UK. The Human Fertilisation and Embryology Authority (HFEA) was authorized to licence and regulate medical centers which wanted to use human mitochondrial donation. In February 2016, the US National Academy of Sciences issued a report describing technologies then current and the surrounding ethical issues.