Justinian's Codex 7.1, De vindicta libertate Berlin, Staatsbibliothek lat. 21, fol. 175v

Medieval Jurists and the Ius commune Digest 2.14.7.16 De pactis Ulpian: Et generaliter quotiens pactum a iure communi remotum est, seruari non oportet. Nec legari, nec iusiurandum de hoc exactum  (F = adactum) ne quis agat servandum. And generally whenever a contract has violated universal legal principles and rights, it should not be considered valid. Neither a legacy nor an oath not to sue is to be enforced. Accursius, Dig. 2.14.7.16 s.v. de hoc exactum: "scilicet pacto inito contra ius commune vel publicum, ut C. de nup. auten. Quod ei<s>, (Authentica to Cod. 5.4.23 [=Nov. 51]), arg. infra de legat. i. Si quis inquillinos § Ultimo (Dig. 30.1.112 [115]) et facit, Cod. de instit. et sub. Reprehendenda (Cod. 6.25.5).