sentences:  In both 2003 and 2004, Siegel played a pivotal role in protecting a form of stem cell research in the United Nations, which was under the threat of being banned by world treaty.In 2003, he brought some of the world’s most prominent stem cell research scientists together at a meeting at the U.N. to educate delegates about the need to ban human reproductive cloning (the cloning of a whole person) while keeping nuclear transfer research (for the cloning of stem cells) legal throughout the world.That very year, the U.N. avoided the passage of a treaty that would have banned nuclear transfer research worldwide by a single vote.