A more thorough explanation:

Sub ballivus (səb bə-lI-vəs), n. [Law Latin] Hist. An undersheriff; a sheriff's deputy. See bailiwick.

Bailiwick (bay-lə-wik). The office, jurisdiction, or district of a bailiff; especially, a bailiff's territorial jurisdiction. It is also termed bailivia, baliva, or balliva.

For example, in the early days, a village was called a "wick." Each village had a bailiff who was its peace officer. His authority was limited to the territory of the wick. A bailiff was popularly referred to as a "bailie," and before long, a bailie's wick was expressed as his "bailiwick." And in time, this word came to be used to indicate the special territory over which a peace officer exercises his authority as such. Although it may be changed by statute, the normal situation is that the bailiwick of a policeman is his city, the bailiwick of a sheriff is his county, and the bailiwick of a state officer, such as a member of the Highway Patrol, is the state."

This definition explains that sub ballivus is a Latin term that refers to an undersheriff or a sheriff's deputy. It also defines bailiwick as the office, jurisdiction, or district of a bailiff, which is a peace officer. The example provided illustrates how the term bailiwick came to be used to indicate the special territory over which a peace officer exercises his authority. It also shows how the bailiwick of different peace officers, such as policemen, sheriffs, and state officers, can vary depending on their jurisdiction.