Stem cell research is a relatively new technology that takes primitive human cells and develops them into most any of the 220 varieties of cells in the human body, including blood cells and brain cells. Some scientists and researchers have great hope for stem cell research and its ability to uncover treatments and possibly even cures for some of the worst diseases including heart disease, diabetes, and neurodegenerative diseases like Alzheimer's and Parkinson's. Along with these hopeful possibilities, stem cell research engenders fears of human cloning and serious concerns over the ethics of conducting scientific research on, which includes the destruction of, human embryos.

Human stem cells primarily come from embryos or adult tissue. Embryonic stem cells can be created solely for the purpose of stem cell research or they can be the leftover embryos from other processes, most likely from in-vitro fertilization (IVF). Fertility treatments usually result in the creation of multiple embryos. Since only the most viable embryos are selected for implantation, some embryos are leftover. The leftover embryos can be discarded, donated to others seeking fertility assistance, preserved, or donated to research. Most commonly, leftover embryos are discarded.

Adult stem cells can be harvested from adult tissue with minor, if any, harm to the adult. Embryonic stem cells, however, are said to be generally easier to extract than the adult stem cells, and embryonic stem cells are said to have more uses than their adult counterparts. Because of their potential uses, and because of questions about when life begins, embryonic stem cells are the primary subject of the stem cell research debate.

The overall debate over the ethics of stem cell research involve two major ethical concerns: (1) the potential for human cloning, and (2) whether these embryos, or pre-embryos as some refer to them, are human life. Perhaps the initial controversy over stem cell research related to the possibility of human cloning. Especially when stem cell research first gained popularity, researchers were concerned with the potential for using stem cells to clone humans. Proponents make many arguments in support of human cloning including the possibility of creating another “you” should body parts or tissues be needed later in life as one may develop illnesses and diseases. Opponents primarily argue that it is not within man’s purview to manufacture, manipulate, or destroy human life.

The other major ethical issue related to stem cell research involves the ongoing debate over when life begins. Some say that life begins at conception and that the use of humans, even immature ones, for research purposes is unethical. Others claim that the embryos are only tiny amounts of undifferentiated tissue and since they are already scheduled for destruction, and have great potential benefit, they should be used to potentially help others.

It is legal to conduct stem cell research in the United States (US), even for the purposes of human cloning. Privately funded laboratories may engage in adult stem cell research or embryonic stem cell research whether the embryos were left over embryos from other processes or were harvested specifically for research. Recent debate centers on whether federal funds should be granted to stem cell research and if so what kind stem cells should be supported by this funding. In 2001, President Bush authorized the issuing of federal funds for stem cell research of over 60 existing stem cells lines. The funding was restricted to these cell lines because the issue of life and death was already decided; that is, the stem cell lines at that point were capable of independent and infinite regeneration.

Many of those that argue for federal funding of stem cell research, including embryonic stem cell research beyond the more than 60 identified stem cell lines, argue that the failure to fund stem cell research has greater ramifications than just limiting that type of research. Federal funds are not given to labs that conduct stem cell research even if the federal dollars are for non-stem cell research. The concern is that federal funds will be used in some way, or to some degree, for stem cell research. As a result, some major US labs have created, at great expense, duplicate laboratories, one dedicated to stem cell research, and another dedicated to non-stem cell research, so federal funds can continue to be received by the non-stem cell research lab.

Other countries permit stem cell research to varying degrees. Countries such as Japan, Sweden, and the United Kingdom have made stem cell research even for purposes of human cloning legal. Countries including Australia, Canada, and France allow adult and leftover embryonic stem cell research but not human cloning. Austria, Ireland, and Poland have some of the most restrictive laws on stem cell research.