The Collaborative International Dictionary of English v.0.48:

Justiciary \Jus*ti"ci*a*ry\, n. [Cf. LL. justitiarius, F.
   justicier. See Justice.] (Old Eng. Law)
   An old name for the judges of the higher English courts.
   [1913 Webster]

   Note: The chief justiciary, or justiciar, in early English
         history, was not only the chief justice of the kingdom,
         but also ex officio regent in the king's absence.
         [1913 Webster]

   Court of justiciary (Scots Law), the supreme criminal
      court, having jurisdiction over the whole of Scotland.
      Justico