Jean Cramer was born in Geneva on 21 June 1701. He studied law at the University of Basel where he obtained his doctoral degree on 30 May 1721 with the dissertation De donationibus. He applied for one of the two chairs in natural and civil law created by the Genevan government in 1723. He delivered a probatory lecture Positiones juridicae de secundis nuptiis on 12 March 1723. In parallel with Jean-Jacques Burlamaqui, he obtained the chair and kept it until 1738 when he was elected to the Small Council of the city. Between 1747 and 1770 he served several times as syndic and once as first syndic. Given the privileges granted to Burlamaqui because of his ill health, Cramer lectured more often on civil than on natural law, that is, on Roman law and on the edicts of Geneva.

Cramer excelled as specialist of local law and wrote down the “Recueil de décisions et d'observations de jurisprudence, à l'usage des juges et des avocats de Genève”, manuscript of 12 volumes, completed in 1758, and the “Commentaire sur les édits de 1713”, manuscript of 14 volumes. As can be gathered from his publications and the manuscripts kept at the Bibliothèque publique et universitaire de Genève, Cramer was heavily involved in the political crisis following the publication of the Social Contract and the Emile by Jean-Jacques Rousseau.