The Collaborative International Dictionary of English v.0.48:

Supersedure \Su*per*se"dure\, n.
   The act of superseding, or setting aside; supersession; as,
   the supersedure of trial by jury. --A. Hamilton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

supersedure
    n 1: act of replacing one person or thing by another especially
         one held to be superior [syn: supersedure,
         supersession]