This halacha discusses the importance of judging favorably instead of accepting lashon hara especially towards the rabbis or those who are righteous and G-D fearing. The extent one should go to judge favorably a sage, rabbi or Jewish court is expressed in the example the note gave.
If a person storms out of Jewish court guilty as charged and goes over to his friend to tell him what happened and in the process of proving his innocence he lashes out at the court claiming they don’t know how to poskin and saying quite a bit of nasty words about them. Even though it sounds like he has a very good case of innocence the person listening still should try to calm down the guilty party and surely not accept anything that he says, for several reasons.
1. It is known, based on a Shach in hilchos Shechita, that baal habatim think differently than Torah sages. So, what they perceive to be logically true might not be what the Torah mandates in halacha.
2. The court can only judge what is presented in front of them and it is possible that a fact which is added, I now might not have been mentioned in litigation so the court poskined based on what they heard and there should not be any claims against them.
3. Even if the case was wrong there is a gemara in Brachos 7b that says there are times where it is decreed in Heaven that someone should lose a court case for whatever reason or maybe the other litigant has a better mazel as the Rosh says elsewhere. But the gemara in Sanhedrin 8a guarantees if there is a misjudgment the guilty party or loser will get the value of his loss somehow at some point.
4. If you see you can’t convince the guilty party to calm down at least you can’t believe what you hear and at the very least you should go over to the rabbis and question them what happened for either they will tell you their reasoning, share with you the sources from where they came up with their psak, or maybe they will realize they were wrong and they will change their psak, which in that case you fulfilled the mitzah of rebuking properly, as the Rambam (hilchos De’os 6:6) says that it’s better to fight out the issue in halacha then to bear ill will against them in your heart.
At the very least one has an obligation to look into the matter before deciding they are wrong and the more one judges others favorably Hashem judges them favorably