This concept was the subject of the first work by 
This concept was the subject of the first work by historian Adrian Sherwin-White, who described how formal documentation of this first appeared on a bronze tablet given to a unit of Spanish cavalrymen. This concept was subdivided into private and public aspects, and a letter of Philip V of Macedon records how this was available to manumitted slaves. This concept was extended by the Constitution of Antoninus, and one could lose this status if subjected to an interdiction from fire and water. In the early days of this status, those who possessed a limited variety of it were denied the ius honorum and ius connubii, while those who enjoyed its full privileges were termed civis optimio iure. The Social War was fought over the failure to extend this status to the Marsi and the Samnites. For 10 points, identify this status, possessing which would render unto one all the privileges associated with living in a certain polity.
This concept was the subject of the first work by historian Adrian Sherwin-White, who described how formal documentation of this first appeared on a bronze tablet given to a unit of Spanish cavalrymen.
Roman citizenship [accept logical equivalents like being a citizen of Rome; accept more specific answers like "being a citizen of the Roman republic" or "being a citizen of the Roman empire"; accept franchise in place of "citizenship"]