The European Court of Justice has banned patenting of any stem-cell process that involves destroying a human embryo.

The capability to convert embryonic stem cells into any type of body tissue makes them potential means of treating a long list of diseases. The court, however, cited ethical reasons and the European directive that biotechnology patents must not imperil “respect for human dignity.”

Stem-cell technology is controversial because some cell lines are derived from embryos. The ECJ decision now endorses widespread protection of human embryos by blocking patents. “A process which involves removal of a stem cell from a human embryo at the blastocyst stage, entailing the destruction of that embryo, cannot be patented,” it said. The blastocyst is the stage just before implantation in the womb, when the embryo consists of around 80 to 100 cells.

Christian groups in Europe welcomed the decision. COMECE, the commission of Catholic bishops conferences in the European Union, said the decision “provides a broad, scientific sound definition of a human embryo. Indeed, fertilization marks the beginning of the biological existence of a human being that undergoes a process of development. Therefore the human embryo, at every stage of development, must be considered a human being with potential, and not just a ‘potential human being.’”

The court said its ruling reflected European law. A European directive on biotechnology patents “intended to exclude any possibility of patentability where respect for human dignity could thereby be affected,” it said. The ruling concerned an invention by Oliver Bruestle of the University of Bonn in Germany for converting human embryonic stem cells into nerve cells. Bruestle said he regretted the decision.