A more thorough explanation:

magna assisa eligenda (pronounced mag-nuh uh-sahy-zuh el-i-jen-duh) is a legal term in Latin that means "of choosing the grand assize." In history, it referred to a writ that ordered a sheriff to summon four knights to give oaths before the justices of assize. These knights would then choose 12 more knights to form a grand assize, which would determine who had the right in a writ of right.

An example of magna assisa eligenda would be a case where two people were claiming ownership of a piece of land. The writ of right would be issued, and the sheriff would be ordered to summon four knights. These knights would swear an oath before the justices of assize and then choose 12 more knights to form the grand assize. The grand assize would then hear the case and determine who had the rightful claim to the land.

Another example would be a case where two people were claiming the right to a title or position. The writ of right would be issued, and the process of summoning the knights and forming the grand assize would be followed to determine who had the rightful claim.

These examples illustrate how magna assisa eligenda was used in medieval times to settle disputes over land, titles, and positions of power.