Ever watch those courtroom dramas on TV or the movies? Or follow real-life courtroom cases?
When the prosecution has a key witness that could seriously damage the case for the accused, or if some small-town joe sues the big corporation for some injustice that was done…the defense attorneys have a favorite strategy: dig for dirt. Look for any damning information about the witness, anything that makes him/her look bad, or dishonest, or whatever, and bring it out in court.