Regalian right was the right of a monarch to receive the income from the estates of a vacant bishopric or abbacy. A liberty was an area where the regalian right did not apply.
History
In England, the exact practice prior to the Norman Conquest of England in 1066 is unclear, but for monasteries it is likely that the bishop or the prior administered the estate, and that the revenues did not go to the king. Under King William the Conqueror, the record is also unclear, but the absence of monastic complaints suggests that revenues did not go to the royal treasury.
In medieval England, King William II was known for keeping bishoprics and abbeys vacant so that his own officials could administer them and keep the income for the king, although recent studies have shown that this was not quite as common as indicated by the complaints of medieval chroniclers. The income from the regalian right was an important, if irregular, source of income for the kings. At least in England under William II, there was a natural tendency to keep the more lucrative offices vacant longer than the poorer offices, thus allowing the royal revenue to be augmented.
Although William's successor, King Henry I at the start of his reign said he would abandon the practice of leaving ecclesiastical offices vacant in order to secure their revenue for himself, events soon required him to exploit the regalian rights also. Henry's most recent biographer, C. Warren Hollister, argued that Henry never intended to renounce the exercise of the regalian right, merely the abuses of it that William II was accused of by the monastic chroniclers.
The Pipe roll from 1130 shows a number of vacant benefices whose revenues were going to the royal coffers. King Henry II continued the practice of using the regalian rights from monasteries, although the king generally allowed a division of revenues between the actual monks and the abbatial office, and did not administer or touch the monks' income. Revenues from the regalian rights were normally paid into the Exchequer, who would record it on the pipe rolls.