There follows a list of some of the subject searches you could use in SOLO. But remember that, if you have already identified a work on your topic in SOLO, you can click on the Details link, then on the hyperlinks in the Subjects line to do an automated subject search.
Law Europe History
Law, Medieval
Justice, Administration of -- Europe -- History
Roman law reception [followed by modern geographic area eg Spain]
Roman law - influence
Law, Frankish
Law, Germanic
Law, Lombard
Law, Visigothic
Ripuarian law
Salic law
Canonists -- Europe -- History -- To 1500 ;
Canon law -- History -- To 1500 ;
Practice of law -- Europe -- History
Law -- Study and teaching -- Europe -- History
Libri feudorum
Feudal law - Europe
Feudalism - Europe
Power (Social sciences) -- Europe -- History -- To 1500
Estates (Social orders) -- Europe -- History -- To 1500
Commercial law -- history
Commercial law -- Europe -- History
Commerce -- History -- Medieval, 500-1500
Europe -- Economic conditions -- To 1492
Europe -- Commerce -- History -- To 1500
Economic development -- Europe -- History -- To 1500
Pay attention to the locations of your search results: you may well find titles across various Bodleian libraries
Les nouveaux mondes juridiques : du Moyen Âge au XVIIe siècle by 
Cultures of Conflict Resolution in Early Modern Europe by 
Women in Law and Law-Making in Nineteenth and Twentieth Century Europe by 
Authority : a sociological history by Useful free websites which happen to have come to our knowledge.... Please check also on the pages in this guide for the various language areas.