A more thorough explanation:

Petite assize is a type of jury trial that decides questions of possession. It is a smaller version of the grand assize, which is a sworn panel summoned to resolve disputes concerning real property. The petite assize is convened to determine who has the right to possess a property or land.

For example, if two people claim ownership of a piece of land, a petite assize may be convened to decide who has the right to possess it. The jury will hear evidence from both parties and make a decision based on the facts presented.

The term "assize" originally meant the sitting of a court or assembly. In the 12th century, certain enactments introduced a new procedure for the trial of questions as to the ownership or possession of lands held by free tenure. The grand assize introduced this new procedure for the determination of questions of ownership, while the possessory assizes were for the determination of questions of possession.