Canon law is the body of laws and regulations made by ecclesiastical authority (Church leadership), for the government of a Christian organization or church and its members. It is the internal ecclesiastical law governing the Catholic Church (both Latin Church and Eastern Catholic Churches), the Eastern and Oriental Orthodox churches, and the individual national churches within the Anglican Communion. The way that such church law is legislated, interpreted and at times adjudicated varies widely among these three bodies of churches. In all three traditions, a canon was originally a rule adopted by a church council; these canons formed the foundation of canon law.

What is the name for the rules issued by the heads of the Church?