On 9 August 2001, US President George W. Bush gave an eleven-minute speech from his ranch in Crawford, Texas, on the ethics and fate of federal funding for stem cell research. Bush also announced the creation of a special council to oversee stem cell research. In the speech President Bush acknowledged the importance of issues surrounding stem cell research to many Americans, presented different arguments in favor of and opposing embryonic stem cell research, and explained his decision to limit but not completely eliminate potential federal funding for embryonic stem cell (ESC) research. The speech was important to embryology as a field because it determined the US government's policy on funding human ESC research for the eight years of George W. Bush's administration.

On 20 November 2009 Democrat Barack Obama replaced Republican George W. Bush as president of the United States. Obama soon initiated changes to Bush's 2001 executive order concerning scientific research involving human stem cells. Stem cell research remains a controversial issue in the US. Some individuals consider it immoral to experiment with an embryo because they regard embryos as human beings from the moment of conception, while others believe stem cell research could lead to great scientific advancements. Congress has not passed any legislation on stem cell research, leaving it open to the president to make policy through executive orders. On 9 March 2009, Obama signed Executive Order 13505 to expand experimentation on stem cells. This overturned Executive Order 13435, which was signed by George W. Bush to limit the potential research that could be done on embryonic stem cells.

On 20 January 2001, Republican George W. Bush was sworn in as the forty-third president of the United States, replacing Democrat William J. Clinton. During his eight years in office, Bush issued many executive orders, often altering previous policy. By signing Order 13435 on 22 June 2007, he changed how stem cell research would be performed in America. The Bush administration was influenced by its commitments to conservative ethical values when constructing this executive order; its goal was to expand stem cell research, but only in ways that did not involve the creation of, or damage to, a human embryo or fetus. This order was developed with the belief that pluripotent stem cells could be researched while still being respectful to human dignity and life. The four sections of Order 13435 provided strict guidelines for future stem cell research.