Collateral issue Meaning, Definition & Usage

Definitions
  1. . (Law) (a) An issue taken upon a matter aside from the merits of the case. (b) An issue raised by a criminal convict who pleads any matter allowed by law in bar of execution, as pardon, diversity of person, etc. (c) A point raised, on cross-examination, aside from the issue fixed by the pleadings, as to which the answer of the witness, when given, cannot subsequently be contradicted by the party asking the question.

Webster 1913