Constitutio Antoniniana
The Constitutio Antoniniana (Latin for: "Constitution [or Edict] of Antoninus") (also called the Edict of Caracalla or the Antonine Constitution) was an edict issued in 212, by the Roman Emperor Caracalla declaring that all free men in the Roman Empire were to be given theoretical Roman citizenship and that all free women in the Empire were to be given the same rights as Roman women.
Before 212, for the most part only inhabitants of Italy held full Roman citizenship. Colonies of Romans established in other provinces, Romans (or their descendants) living in provinces, the inhabitants of various cities throughout the Empire, and small numbers of local nobles (such as kings of client countries) held full citizenship also. Provincials, on the other hand, were usually non-citizens, although some held the Latin Right.
Analysis
The Roman jurist Ulpian's Digest stated, "All persons throughout the Roman world were made Roman citizens by an edict of the Emperor Antoninus Caracas."