These laws may be divided into three heads:  first, laws relating to the protection and privileges allowed to mariners by the Roman emperors; secondly, laws relating to particular fleets; and lastly, laws relating to particular branches of trade.

1.  The fifth title of the thirteenth book of the Theodosian code of laws entirely relates to the privileges of mariners.  It appears, from this, that by a law made by the Emperor Constans, and confirmed by Julian, protection was granted to them from all personal injuries; and it was expressly ordered, that they should enjoy perfect security, and be defended from all sort of violence and injustice.  The emperor Justinian considered this law so indispensably necessary to secure the object which it had in view, that he not only adopted it into his famous code, but decreed that whoever should seize and apply the ships of mariners, against their wishes, to any other purpose than that for which they were designed, should be punished with death.  In the same part of his code, he repeats and confirms a law of the emperors Valentinian, Valens, and Gratian, inflicting death on any one who should insult seafaring men.  In another law, adopted into the same code from the statutes of former emperors, judges and magistrates are forbidden, on pain of death, to give them any manner of trouble.  They were also exempted from paying tribute, though the same law which exempts them, taxes merchants.  No person who had exercised any mean or dishonourable employment was allowed to become a mariner; and the emperors Constantine and Julian raised them to the dignity of knights, and, shortly afterwards, they were declared capable of being admitted into the senate.

As a counterbalance to those privileges and honours, it appears, that mariners, at least such of them as might be required for the protection of the state, were obliged to conform themselves to certain rules and conditions, otherwise the laws already quoted did not benefit them.  They were obliged to possess certain lands; and, indeed, it would seem that the profession and privileges of a mariner depended on his retaining these lands.  When these lands were sold, the purchaser was obliged to perform towards the state all those services which were required of a mariner, and in return he obtained all the privileges, dignities, and exemptions granted to that class of men.  This, however, was productive of great inconvenience to the state; since, if the lands were purchased by persons ignorant of maritime affairs, they could not be so effective as persons accustomed to the sea.  From this consideration a law was passed, that when such lands as were held on condition of sea-service passed into the possession of those who were unaccustomed to the sea, they should revert to their original owners.  It was also ordered, that such privileged mariners should punctually perform all services required of them by the state; that they should not object to carry any particular merchandize; that they should