The Collaborative International Dictionary of English v.0.48:

Filacer \Fil"a*cer\, n. [OE. filace a file, or thread, on which
   the records of the courts of justice were strung, F. filasse
   tow of flax or hemp, fr. L. filum thread.] (Eng. Law)
   A former officer in the English Court of Common Pleas; -- so
   called because he filed the writs on which he made out
   process. [Obs.] --Burrill.
   [1913 Webster]