Policies vary by country, by region and even by university. They govern whether research can be performed or funded on human embryos themselves and cells made from human embryos. Other policies also require researchers to show that certain stem cell therapies are likely to be safe before testing them in people.
Some kinds of research are ineligible for government research funding; some kinds of research require approval by government or university officials, and some research is banned outright. The specifics vary by country, by region and even by institution. In some countries research materials and tools are covered by patents and so require researchers to obtain permission from patent holders before beginning experiments.
In the United States, scientists cannot use federal funding for research on human embryonic stem cells created after August 2001, when Bush articulated his policy. As of April 2007, attempts by the U.S. Congress to overturn this policy have failed. However, creating new human embryonic stem cell lines and conducting research on them is legal, so long as federal funding is not used.
Scientists in the UK and Australia must receive government permission to use early human embryos to create new stem cell lines. In the United States this research is covered under state laws. Generally, getting permission requires that embryos are acquired with appropriate informed consent, that the experiments promise to yield useful information and that the embryos will not be allowed to grow longer than 2 weeks. Two weeks marks the point when the embryo is no longer capable of “twinning” and so crosses the threshold of individuality.