A more thorough explanation:

Palace Court was a court that had jurisdiction over all personal actions that arose within 12 miles of Whitehall. It was created by James I in response to complaints about the inconvenience of using the itinerant Court of the Marshalsea. Its jurisdiction was similar to the Court of the Marshalsea, but the court remained in Whitehall. It was abolished along with the Court of the Marshalsea in 1849.

For example, if someone living within 12 miles of Whitehall had a personal legal dispute with someone else, they could bring their case to Palace Court for resolution.

The court of the marshalsea, and the palace court at Westminster, though two distinct courts, are frequently confounded together. The former was originally holden before the steward and marshal of the king's house, and was instituted to administer justice between the king's domestic servants, that they might not be drawn into other courts, and thereby the king lose their service.... But this court being ambulatory, and obliged to follow the king in all his progresses, so that by the removal of the household, actions were frequently discontinued, and doubts having arisen as to the extent of its jurisdiction ... [the king] erected a new court of record, called the curia palatii, or palace-court, to be held before the steward of the household and knight marshal, and the steward of the court, or his deputy; with jurisdiction to hold plea of all manner of personal actions whatsoever, which shall arise between any parties within twelve miles of his majesty's palace at Whitehall.”

This definition explains that Palace Court was created to provide a more convenient option for resolving legal disputes within a certain geographic area. It also provides historical context for the court's creation and its relationship to the Court of the Marshalsea.