Should genetically engineered animals be patented? This issue has been one of the most contentious as lawmakers have grappled with how best to protect intellectual property. Since the 1980 case of Diamond v. Chakrabarty, in which the U.S. Supreme Court ruled that a living microorganism is patentable, the U.S. Patent and Trademark Office has determined that plants and nonhuman animals can be patented. These policy decisions have led to congressional debate on whether animals should be patentable subject matter. Patenting of living organisms is unique for three reasons: the invention itself is alive; the invention in some instances can reproduce itself; and the invention sometimes cannot be adequately described for patent specification purposes, leading to the need for deposit of the invention for patent purposes.