A more thorough explanation:

A legatine constitution is a set of laws created by a papal legate, who is a representative of the Pope. These laws are related to the practices and beliefs of the Christian Church.

For example, in England, there were two national synods in 1220 and 1268 where legatine constitutions were enacted. These laws were created by the papal legate and were related to the administration of the Church, the conduct of the clergy, and the punishment of heretics.

These examples illustrate how a legatine constitution is a set of laws created by a papal legate and how they were used in England to regulate the practices and beliefs of the Christian Church.