Who administers direct democracy mechanisms at the national level?

Constitution of Uruguay (Constitución dela República Oriental del Uruguay),

http://www.refworld.org/docid/3ae6b5600.html

Article 322.

There shall be an Electoral Court which shallhave the following powers in addition to those established in Section III orwhich may be prescribed by law:

a)To act in all matters relating to electoralacts or procedures;

b)To exercise directive, disciplinary,advisory, and economic supervision over electoral organs;

c)To render final decision on all appeals andclaims that may arise and act as judge of the elections to all electiveoffices, and of plebiscites and referendums.