A German brother and sister who live as a couple and have four children are going to Germany's highest court to try to legalise their relationship.
The 29-year-old brother has already spent more than two years in prison for sleeping with his sister, and could be incarcerated again, his lawyer said.
The pair are currently drawing up an appeal to take before Germany's constitutional court.
They argue they are being denied the right to sexual freedom.
Modern attitudes seem to hold that laws against incest are merely the relic of outmoded attempts at eugenics, so they should go. It's a victimless crime, right?