The Constitutio Antoniniana, issued in 212 AD by Emperor Caracalla, granted Roman citizenship to all free inhabitants of the Roman Empire. This significant decree aimed to unify the diverse populations under Roman rule and increase tax revenue. By extending citizenship, the Constitutio also allowed more people to participate in the legal and political systems of Rome. This move was part of Caracalla's broader strategy to strengthen his authority and promote loyalty among the empire's subjects, ultimately reshaping the social landscape of the Roman world.