In vitro fertilization treatment can be painful and tiring, but for Natallie Evans, it turned out to be devastating. The British woman froze six embryos created with her fiancé, Howard Johnston, in 2001, after she was diagnosed with cancer. After the couple broke up, he legally blocked her from using the embryos, saying he didn't want the burdens of fatherhood.

Last week, the European Court of Human Rights in Strasbourg sided with Johnston, upholding a British law that says that either party can revoke consent before the embryos are transferred to the woman's womb. That may or may...