The Collaborative International Dictionary of English v.0.48:

Perempt \Per*empt"\, v. t. [L. peremptus, p. p. of perimere to
   take away entirely, to destroy; per (see Per-) + OL. emere
   to take. See Redeem.] (Law)
   To destroy; to defeat. [R.] --Ayliffe.
   [1913 Webster]