The 13th Amendment of the U.S. Constitution forbids any grant of property rights in a human being. That much is clear. But science and technology are moving far faster than legal systems, blurring traditional boundaries and definitions.

Bioengineers have inserted foreign genes, including human genes, into the chromosomes of many animals, including pigs, sheep, goats and chickens. In the future, genetic engineering will enable scientists to intermingle the genetic material of humans and animals to produce human-animal hybrids. "It may be possible," writes one commentator, "to patent and to enslave human-animal hybrids who think and feel like humans but who lack constitutional protection under the 13th Amendment."Given that animals containing human genes are already patentable, will it be possible to patent human-animal hybrids? Some are calling on US courts to begin developing a legal theory of "constitutional personhood" that can be applied to genetically engineered species, and afford them protection under the US Constitution.

Rick Weiss