The Senatus of Sydney governs all Legion of Mary groups in NSW, in the ACT-Goulburn Diocese, in the Dioceses of Honiara and Malaita in the Solomon Islands and in Dili (in Timor Leste).

The Legion of Mary is a Lay Catholic Organisation that follows a definite hierarchical system of governance.
 
The basic unit of the Legion of Mary in each Parish is the Praesidium.
 
Two or more Praesidia report on works, functions and for support to the Curia.
 
The Comitium is a Curia to which its own attached Praesidia and other Curiae are attached for reports, functions and support.
 
The Regia governs a large area, including Comitia, Curiae and Its own attached Praesidia. It reports to a Senatus or directly to Concilium Legionis Mariae in Dublin.
 
The Senatus governs its own attached Praesidia and any other Councils within its designated area. It reports directly to Concilium Legionis Mariae in Dublin.
 
The highest Council is The Concilium Legionis Mariae in Dublin. It has the final say in all matters.