Utroque iuris

A Doctor of Canon and Civil Law, from the Latin doctor utriusque juris, or juris utriusque doctor, or doctor juris utriusque ("doctor of both laws") (abbreviations include: JUD, IUD, DUJ, JUDr., DUI, DJU, Dr.iur.utr., Dr.jur.utr., DIU, UJD and UID) is a scholar who has acquired a doctorate in both civil law and church law. The degree was common among Catholic and German scholars of the Middle Ages and early modern times. Today the degree is awarded by the Pontifical Lateran University in the State of the Vatican City after a period of six years study, by the University of Wuerzburg, and by the University of Fribourg.

Prior to ca. 1800, people who studied law in Europe, studied canon law, Roman law, and feudal law. These laws were the constituent parts of the Ius commune. The Ius commune was a pan-European legal system that held sway over Europe from approximately the twelfth through the eighteenth century. Graduates earned the decree of Doctor of both laws, because they had to study both canon law and civil law, in order to master the Ius commune.

...
Wikipedia