The Federalist No. 10
"No man is allowed to be a judge in his own cause, because his interest would certainly bias his judgment, and, not improbably, corrupt his integrity. With equal, nay with greater reason, a body of men are unfit to be both judges and parties at the same time; yet what are many of the most important acts of legislation, but so many judicial determinations, not indeed concerning the rights of single persons, but concerning the rights of large bodies of citizens?"
What I believe it's states in this passage is that no person can be or should be both the judge and party at the same time becuase it would be impossible to see both sides when that person is being both. He or she is only going to look after their own point of view. Its easy and more convenient when you have to judge others because you would see the situation from an outsider and not from one of the sides.
I've picked this passage because it's something I believe is happening now a days. People are judging others by giving their own opinion of that particular situation. Instead of them gathering the facts about that particular subject, they just give their two senses. They Judge with out thinking of the outcome or the situation ahead of time.