Medieval law

Internet Medieval Sourcebook: Medieval Legal History
Otto Vervaart: Medieval law
Law-related Internet Project: Roman law
Ius Romanum

Canon law
Ius commune

Scots legal dictionary
ius: right recognised by law (also jus)
ius ad rem: right to a thing (personal right) (jus ad rem)
ius in personam: personal right (also jus in personam)
ius in rem: right in a thing (real right) (also jus in rem)
ius naturale: natural justice (alsojus naturale)

SEP on rights

Kenneth Pennington (website)
Tryanny of a Concept; check also syllabus for Roman Law and the Ius Commune
The History of Rights in Western Thought

Check Gratian. What instances of ius are there in actual legal codes? Is it defined by an authority other than the commentators?