He launched a lawsuit at Munich's medical malpractice court in order to get out of the payments, saying the clinic should pay instead.
But judges ruled otherwise on Wednesday, saying he had not been clear enough with the clinic when he called to revoke his permission for the embryos to be used.
Staff at the clinic also had no reason to doubt the authenticity of the signatures and so could not be liable, the judges added.
The decision is not legally binding, according to DW. It is not clear if Karl plans to appeal the ruling.
German courts do not typically give the surnames of people involved in cases for privacy reasons.