Practice by lawyers in foreign jurisdictions is not a new phenomenon. Long before national states arose and imposed borders and passport controls, empires ruled over people with diverse ethnic and religious backgrounds. To varying degrees, the Hellenic, Roman, and Ottoman empires applied law according to their subjects' ethnic, religious, or social status and not uniformly according to territorial standards. The coexistence of different legal systems within the same territory was the rule and inevitably resulted in the legal profession - or its equivalent - being very diverse. In the Roman era and beyond, consuls were appointed to travel on board ships during long sea voyages in order to administer the laws of the country of flag. Gradually, their jurisdiction extended not only to seamen on ship and in the port of call but also to all nationals of the country to which the consul was accredited.
Kenneth S. Kilimnik, Lawyers Abroad: New Rules for Practice in a Global Economy, 12 Penn St. Int'l L. Rev. 269 (1994).