Scientists who conduct research involving the destruction of human embryos are subject to excommunication, the president of the Pontifical Council for the Family has warned.

This is only right; research on embryos kill a living human person.

UPDATE: The Curt Jester makes an amusing point as to why Catholic politicians who promote laws that endorse or allow embryonic stem-cell research or abortion are not automatically excommunicated ("latae sententiae" is the official phrase): "it does not apply if 'a person who lacked the use of reason,..."