Katherine Jackson just got shut down by an L.A. judge ... who REJECTED her bid for a new trial in the Michael Jackson wrongful death case.
A jury shut Katherine down in October ... ruling AEG Live did not screw up in hiring Dr. Conrad Murray.
Katherine claimed jurors had been given confusing instructions ... but the judge wasn't buying what she was selling.
Katherine's recourse now is to take up her beef with the California Court of Appeal. She's already filed legal docs with the court.