Within the medieval Catholic Church, the term ‘clandestine betrothal’ was associated with the absence of witnesses, solemnities, and other formalities. Parental consent was not a legal requirement for betrothal or marriage, which was based on the free decision of the spouses. Indeed, marriage was a sacrament based on the free consent of the spouses. As long as the parties gave their free consent, the marriage was valid; parental consent was not an essential element. However, Martin Luther held that the will of the parties was not sufficient, because the couple was joined by God, and God’s will was reflected in parental consent. A marriage should be contracted in the presence of the parents, because without their authorization there would be no way to prove that the marriage was God's will. Obedience to one's parents was obedience to God. Luther intended the parents to be a public authority, and he therefore proposed a different definition of clandestine marriage that combined the absence of witnesses with the lack of parental approval. For Luther, the presence of witnesses was not enough to constitute the publicity of a marriage, as the witnesses did not have the public authority to establish a marriage. The parents were the public authority that also had to be present: they signaled God’s will.
Medieval canonists had enumerated numerous types of clandestine betrothal (three, four, six etc.). However, the Lutheran jurists Johannes Schneidewin, Conrad Mauser, and Joachim von Beust translated Luther’s definition into legal terms, reducing the types of clandestine betrothal to only two. The first type, absence of witnesses, continued to be regulated by canon law, with some exceptions. The second, lack of parental approval, was governed by Roman law reinterpreted according to Scripture. Cardinal Bellarmine criticized this definition as it had confused marriage without parental consent with clandestine marriage. The Lutheran theologians Paul Tarnov and Johann Gerhard replied that ‘clandestine’ had acquired a new meaning: violation of the law imposing parental approval. In other words, Tarnov and Gerhard clarified that in the Lutheran definition of clandestine marriage, the adjective ‘clandestine’ was employed to delimit not only the absence of publicity, but also the lack of parental approval. A clandestine marriage was a marriage that breached the divine order. In this sense it was not clandestine because of the location, but because of the manner (non tam a loco quam a modo): it was contracted in violation of divine law and civil law. Benedict Carpzov repeated these teachings and thus showed how the work of the early Reformers had taken hold in legal thought.