First, make sure your letterhead on all your documents explicitly points out that you're under color of MARITIME LAW. Next, be sure to state emphatically you don't recognize the judge's standing in the courtroom. Let them know that you are actually the judge presiding over the case and threaten the former-judge with contempt if they object. Finally, before you go to court, make a business card securing your position as the new presiding judge of the courtroom and, this is key, get it laminated!!!! They can't overturn your ascension to the bench as long as the card is laminated due to this making it impervious to all written law.

Congratulations. You just won your case.