In Shadowlands the Hierarchy rules over the Western dead, specifically Europe, The Americas, and to a certain extent, countries colonized by them (such as Australia). Founded by Charon as means of unifying and ordering the chaotic afterlife, it has grown into a stratified, calcified bureaucracy "led" by battling Deathlords and based upon the enslavement of thousands of souls for use as Thralls or raw materials.
Criminalizing any opposition and crushing those who stand in their way, this bureaucracy primarily operates through its eight armored Legions who have rolled across the oceans to make sure Stygian law is maintained throughout the Deadlands. In addition to these Legions, wraiths may belong to one or more Guilds, some of them in secrecy, some official. The exact governing structure of the Hierarchy is in constant change; it was originally designed to operate under the auspices of Charon, whose disappearance in 1945 during his fight with Gorool has thrown the entire organization into the "leadership" of battling Deathlords.
Hierarchical society is just as driven by the weight of massive tradition as by legal status. This is at least partly because the Hierarchy's continued existence is something of a feedback loop: older wraiths transfer passions to maintaining the Hierarchy, and the Hierarchy exists to provide older wraiths a place for those passions.
Following the events in Ends of Empire, the Hierarchy is effectively destroyed.