The Collaborative International Dictionary of English v.0.48:

Precedential \Prec`e*den"tial\, a.
   Of the nature of a precedent; having force as an example for
   imitation; as, precedential transactions.
   [1913 Webster]

         All their actions in that time are not precedential to
         warrant posterity.                       --Fuller.
   [1913 Webster]

WordNet (r) 3.0 (2006):

precedential
    adj 1: having precedence (especially because of longer service);
           "precedential treatment for senior members of the firm"