A question, I sometimes wonder, is, how one could give 'proof' of Roman citizenship? Did they have identity documents confirming this? How about it in the provinces? Was citizenship a collective status, granted to the whole population in a province? If not, suppose you are a citizen, get into trouble in some remote spot of the Roman Empire. Risking crucifixion, can I claim "I am a Roman citizen!", and will justice inquire about it first, or will the judges just reply "That's what they all say!" and order a swift crucifixion, for good measure os setting an example! Could an individual's citizenship be revoked in some cases? And what about the Christians in Rome under persecutions? Were they no citizens, or did the emperor not bother about it, when he had them crucified in the circus?