Complete Monster: John Milton (aka Satan) runs an Occult Law Firm staffed by his demons and humans he corrupted. He exploits the legal system to get as many violent criminals off the hook and spread corruption everywhere in the world, hoping that the Earth will become such a perversion that it will hurt Heaven and spite God. Having to work around the free will of humans, he subtly manipulates them to give in to evil instead. He seduces multiple women over the years so he can find offspring good enough to mate with each other and further produce The Antichrist. He drives Kevin's wife Mary Ann to madness and suicide, and rapes her for half a day, leaving her with scratch and bite marks all over her body. He later taunts his son Kevin with this crime in an especially vile Post-Rape Taunt. He brutally kills anyone within his company who tries to expose his corruption. When Kevin destroys his plan by killing himself, he kills his daughter to vent his anger by turning her into a withered husk.
Al Pacino's Devil is well dressed and suave (in his own creepy way), and seems to get any woman he wants.
Christabella, who is played by the gorgeous Connie Nielsen.
Family-Unfriendly Aesop: The idea that even the guilty should be competently defended? That's the Devil's work. Criminal defense attorneys should only defend the innocent.
On the other hand, one could say the Aesop is that competent legal defense shouldn't be dependent on one's station. Milton's law firm is ridiculously expensive, so the only people who could possibly afford them are the richest of the rich - meaning the rest of society loses by default. After all, Milton's methods are entirely legal - see Analysis / Amoral Attorney.
Genius Bonus: When Kevin Lomax wins his final case, he completes 66 court victories in a row, a number very similar with 666, which is associated with the devil. Also, when he is at the hospital where Mary Ann is placed, he signs her papers with the left-hand, which was culturally associated with the angel of death and those who have fallen out of God's favor.
Milton: Well... On a scale of one to ten, ten being the most depraved act of sexual theater known to man, one being your average Friday night run-through at the Lomax household, I'd say, not to be immodest, Mary Ann and I got it on at about....(cue the creepy yet funny face) seven.