Sir

You report that the US patent office has rejected a bid by Stuart Newman and Jeremy Rifkin to patent techniques for creating a human-animal hybrid (Nature 399, 626; 1999). In rejecting their claim, the examiner informed the would-be inventors that the US Patent Act does not cover the patenting of humans. Although the examiner is correct that property rights in a human cannot be granted under US law, the Newman-Rifkin invention raises a different question, as only a part of it is human. But even something that is only part human — a quasi-person — cannot be patented, according to constitutional law.

To be granted a patent in the United States, an invention must be new, useful and not obvious to a person skilled in the pertinent scientific discipline. In 1976, Chakrabarty tried to patent a bacterium genetically engineered to digest oil but, although the bug satisfied all three criteria, the patent office refused to grant a patent on the grounds that living organisms could not be patented. The Supreme Court overturned this decision, concluding that “Anything man-made under the sun can be patented”.

That opened the door for patents on engineered, living organisms. Did it make humans patentable? A human being is ‘man-made’ (woman-made, too, of course) so it satisfies the first level of inquiry set out by the Supreme Court. A human is also new (the combination of genes is novel), useful, and not obvious (no one could predict what maternal and paternal genes would come together nor the resulting phenotype). All the criteria to earn a patent are met.

But the matter is not settled so simply. Patented inventions become the personal property of the inventors to dispose of as they see fit. However, under US law, a human cannot be held as property. The thirteenth amendment to the constitution, which ended slavery, prohibits taking property rights in human beings. A human, therefore, cannot be patented.

What about the patentability of hybrids? Rifkin suggests that the answer requires the patent office to define the maximum quantity of humanness that can be present in an organism for it to be considered patentable. But this analysis has already been done. Not only does the thirteenth amendment prohibit the ownership of a person, but it also forbids property rights in a quasi-person. When the constitution was framed in 1787, it contained a provision that slaves were to be counted as three-fifths of a person for the purpose of apportioning representatives to the Congress. The goal of the amendment was to outlaw slavery — to bar the ownership of Black people. But it did not change the legal status of Black people. They remained part-people (quasi-people) who were not entitled to vote, citizenship, or other rights. It was not until the fourteenth amendment was passed that Black people were made citizens and granted full personhood under the constitution.

The thirteenth amendment stood for the proposition that a quasi-person was not property to be held by another. So the patent office is correct in refusing to grant a patent on an organism that is only part human.