Christopher Reeve has joined scientists in a lawsuit aimed at overturning a government decision to stop funding stem cell research, the BBC reports. Research funding was halted after ethical debates started over the harvesting of stem cells, usually taken from embryos left over after fertility treatments and from aborted fetuses. The lawsuit alleges that the George W. Bush administration has not gone through the proper channels necessary to stop the research. According to the BBC, doctors believe that stem cell therapies may one day serve as a source of replacements for cells destroyed by disease, though very few clinical trials have shown a clear benefit to patients, if at all. Reeve, who played the cartoon superhero Superman in four films, said that he believes stem cell research will allow him to walk again and should be resumed immediately. He has been a leading advocate of medical research since a horse-riding accident left him paralyzed several years ago.