Pity for One who Murdered or Maimed
"And your eye shall not have pity"—Deuteronomy 19:21.
A judge may not have pity and show leniency on one who murdered or maimed another. He may not say, "This poor person unintentionally amputated his fellow's arm, or knocked out his eye," and then show leniency with regards to the requisite restitution. [And similarly with regards to showing mercy in a capital case.]
Favoring an Indigent Defendant
"You shall not favor a poor man in his cause"—Exodus 23:3.
A judge may not have mercy on an indigent litigant and improperly rule in his favor. The judge may not think, "This litigant is poor, and both the rich person [who is suing him] and I are commanded to provide for his sustenance. I will therefore rule in his favor and he will thus have his needs met in an honorable fashion."
Rather, a judge may not differentiate between the wealthy and the destitute, and if the law calls for it, he must find the poor person guilty and require him to pay that which he owes.
Favoring a Litigant
"You shall not honor an important person"—Leviticus 19:15.
A judge may not show favoritism to one of the litigants in the course of a trial, even if that individual is a highly respected and great person. The judge may not accord him honor or demonstrate any sign of favoritism whatsoever.
Condemning an Evil Litigant
"You shall not pervert the judgment of the impoverished in his cause"—Exodus 23:6.
A judge is enjoined not to rule against a litigant due to the fact that he is known to be an evil sinner. In the words of our Sages, "An upright person and an evil person are standing before you in trial. You may not say, 'Since he is evil, I will rule against him.'"
(The Sages understand the word "impoverished" in the afore-cited verse as meaning "impoverished in good deeds.")
Dispensing Proper Justice
"You shall do no unrighteousness in judgment"—Leviticus 19:15.
A judge is forbidden from distorting justice; he may not deviate from the Torah law regarding a case's verdict.