Brittany Donovan was born 13 years ago in Pennsylvania. Her biological father was sperm donor G738. Unbeknownst to Brittany's mother, G738 carried a genetic defect known as fragile X-a mutation that all female children born from his sperm will inherit, and which causes mental impairment, behavioral problems and a typical social development.

Last week, Brittany was given the green light to sue the sperm bank, Idant Laboratories of New York, under the state's product liability laws. These laws were designed to allow consumers to seek compensation from companies whose products are defective and cause harm. Nobody expected them to be applied to donor sperm.

Thousands of people in the U.S. have purchased sperm from sperm banks on the promise that the donor's history has been carefully scrutinized and his sample rigorously tested, only for some of them to discover that they have been sold a batch of bad seed. Some parents learn about genetic anomalies after their disabled child is born and they press the sperm bank for more information. Others realize it when they contact biological half-siblings who have the same disorder.

So will Donovan vs Idant Laboratories open the floodgates? It seems unlikely. New York's product liability laws are highly unusual in that they consider donor sperm to be a product just like any other. Most other U.S. states grant special status to blood products and body parts, including sperm. In these states, donor sperm is not considered a "product" in the usual sense, despite the fact that it is tested, processed, packaged, catalogued, marketed and sold. Similarly, European Union product liability law could not be used in this way.

Even if this lawsuit is an isolated case, it still raises some difficult question. First, to what lengths should sperm banks go to ensure they are supplying defect-free sperm? As we learn more and more about human genetics, there is a growing list of taste that could be performed. Nobody would deny that donor sperm carrying the fragile X mutation should be screened out—and there is a test that can do so—but what about more subtle defects, such as language impairment or susceptibility to early Alzheimer's?

Donovan vs Idant Laboratories also serves as a reminder of the nature of the trade in human gametes. Sperm bank catalogues can give the impression that babies are as guaranteed as dishwashers. The Donovans are entitled to their day in court, but in allowing the product liability laws to be used in this way, the legal system is not doing much to dispel that notion.