The Roman governor was an official (elected or appointed) to be the chief administrator of Roman law throughout one or more of the many provinces constituting the Roman Empire. The generic term in Roman legal language was Rector provinciae.

By the time of the early empire, there were two types of provinces — senatorial and imperial — and several types of governor would emerge. Only proconsuls and propraetors fell under the classification of promagistrate. The governor of any Roman province had many tasks to carry out during his administration.

Firstly, he was responsible for taxation and financial management. Depending on the basis of his appointment, he was either the Emperor's personal agent, or the Roman Senate’s financial agent, and had to supervise the local authorities, the private tax collectors, and levy taxes. A governor could mint coins and negotiate with wealthy institutions such as temples and private money-lenders that could advance money. The governor was also the province's chief accountant. He inspected the books of major cities and various operations as well as supervising large-scale building projects throughout the province. He would also need to keep the peace between countries

Secondly, the governor was the province's chief judge. The governor had the sole right to impose capital punishment, and capital cases were normally tried before him. To appeal a governor's decision necessitated travelling to Rome and presenting one's case before either the Praetor Urbanus, or even the Emperor himself, an expensive, and thus rare, process. An appeal was unlikely to succeed anyway, as a governor wouldn’t generally take the chance of convicting someone contrary to the Emperor's wishes. The governor was also supposed to travel across his province to administer justice in the major towns where his attention was required.

Finally and most importantly, he commanded the military forces within the province. In the more important provinces, this could consist of legions, but elsewhere, there were only auxiliaries. As a part of his standing orders the governor had the authority to use his legions to stamp out organized criminal gangs or rebels in the area without need for the Emperor's or Senate's approval.

Every governor had at his disposal a diversity of advisors and staff, who were known as his comites (Latin for "companions"); the number of these depended on the governor's social standing and rank. These comites would serve as the governor's executive council, with each supervising a different aspect of the province, and assisting the governor in decision making. In the provinces with a significant legionary presence, the governor's second-in-command was usually a quaestor, a man elected in Rome and sent to the province to serve a mainly financial role, but who could command the military with the governor's approval. In other provinces, governors themselves appointed non-magistrate prefects or procurators to govern a small part of the province and act as their second-in-command.

This text is from WIKI