Their challenge ensures that it will be months, at the earliest, before the government can begin to license any research.
On Monday, Britain's parliament passed new regulations under the 1990 Human Fertilization and Embryology Act that legalize the destruction of embryos for stem cell research, and, in a global first, permitted cloning to create human embryos for the research.
Regulators have said they will not authorize the creation of cloned babies, but the ProLife Alliance says it believes there is a loophole in the law.
The group intends to argue that embryos created by cloning do not fit the definition of embryo under the 1990 act because fertilization is not involved. Therefore, the group contends, such cloned embryos are not subject to regulation under the act, which would mean the parliamentary vote was invalid.
Justice Jeremy Sullivan said the case will not come to court before June, and it could be later in the summer before a ruling is given.
"This is a case where it is better to get it right than get it rushed," Sullivan said.
ProLife acknowledged government plans to introduce new primary legislation to ban human reproductive cloning, but said it feared ministers have failed to appreciate the urgency of the situation.
"Confusion increases as the government claims on one hand that cloning is covered by the act, while at the same time suggesting that a specific bill will be necessary to prohibit reproductive cloning," the group said in a statement.
Cloned embryos would be made by replacing the nucleus of an egg with that of a cell taken from a person's body, then chemically or electrically prompted to grow into an embryo. The embryo would be genetically identical to the person who's cell was inserted in the egg.
Scientists believe that by creating cloned embryos from patients, they will be able to extract stem cells that are perfectly matched for transplant. Stem cells are the master cells found in embryos that give rise to all other cells in the body. Doctors hope they will be able to cure or treat hundreds of diseases by directing stem cells to develop into any type of tissue needed for transplant.
Extracting stem cells involves destroying the embryo.
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