The city of Philippi was a Roman colony (Acts 16:12), i.e., a military settlement of Roman soldiers and citizens, planted there to keep in subjection a newly-conquered district. A colony was Rome in miniature, under Roman municipal law, but governed by military officers (praetors and lictors), not by proconsuls. It had an independent internal government, the jus Italicum; i.e., the privileges of Italian citizens.

a designation of Philippi, in (Acts 16:12) After the battle of Actium, Augustus assigned to his veterans those parts of Italy which had espoused the cause of Antony, and transported many of the expelled inhabitants to Philippi, Dyrrhachium and other cities. In this way Philippi was made a Roman colony with the “Jus Italicum.” At first the colonists were all Roman citizens, and entitled to vote at Rome.