The Collaborative International Dictionary of English v.0.48:

Deforce \De*force"\, v. t. [imp. & p. p. Deforced; p. pr. &
   vb. n. Deforcing.] [OF. deforcier; de- or des- (L. de or
   dis-) + forcier, F. forcer. See Force, v.] (Law)
      (a) To keep from the rightful owner; to withhold
          wrongfully the possession of, as of lands or a
          freehold.
      (b) (Scots Law) To resist the execution of the law; to
          oppose by force, as an officer in the execution of his
          duty. --Burrill.
          [1913 Webster]