The Collaborative International Dictionary of English v.0.48:

Impanel \Im*pan"el\, v. t. [imp. & p. p. Impaneledor
   Impanelled; p. pr. & vb. n. Impaneling or Impanelling.]
   [Pref. im- in + panel. Cf. Empanel.] [Written also
   empanel.]
   To enter in a list, or on a piece of parchment, called a
   panel; to form or enroll, as a list of jurors in a court of
   justice. --Blackstone.
   [1913 Webster]