US government funding for research using embryonic stem cells has been thrown into disarray after a judge ruled that it violates laws prohibiting the destruction of human embryos.

The effect of the temporary injunction, by district court judge Royce Lamberth, bars federal funding for studies on stem cells derived from human embryos that are later discarded, which had been allowed by President Obama's executive order last year.

The judge ruled that the research violated the Dickey-Wicker amendment first passed by Congress in 1995, which outlawed the use of taxpayer funds to carry out any "research in which a human embryo or embryos are destroyed".

The New York Times reported that the ruling came as a shock to scientists at the National Institutes of Health and at medical research universities across the US: "Scientists scrambled Monday evening to assess the ruling's immediate impact on their work."

The injunction appears to set the scientific clock back to President Bush's executive order restricting federally-funded research to stem cells already in existence by August 2001. But some scientists fear that the scope of the latest ruling may even prohibit research on that basis, since the limited lines of stem cells allowed under the Bush regulations were also derived from human embryos.

The Bush-era policy was overturned by President Obama's executive order in 2009, allowing government funding for research on stem cells produced by privately-funded labs and derived from embryos that would otherwise have been disposed of after IVF treatment. The Obama order allowed the National Institutes for Health (NIH) to set ethics guidelines over which cell lines would qualify for funding.

In his ruling [pdf], Judge Lamberth said: "The Dickey-Wicker Amendment is unambiguous. It prohibits research in which a human embryo is destroyed, discarded, or knowingly subject to risk of injury or death greater than that allowed under applicable regulations. The guidelines violate that prohibition by allowing federal funding of [embryonic stem cell] research because ESC research depends upon the destruction of a human embryo."



The case against the US government was brought by two doctors, James Sherely and Theresa Diesher, who use adult stem cells in their research. They argued that the NIH guidelines broke the Dickey-Wicker amendment, and that their careers were harmed by having to compete for government funding with researchers using embryonic cells.

The judge's decision is almost certain to be appealed by the administration but it does confirm fears at the time of President Obama's order that an executive ruling would provide weaker protection for funding than legislation passed by Congress.