"Is it the part of the police department to harass me when this city is a flagrant vice capital of the civilized world?" Ignatius bellowed over the crowd in front of the store. "This city is famous for its gamblers, prostitutes, exhibitionists, Antichrists, alcoholics, sodomites, drug addicts, fetishists, onanists, pornographers, frauds, jades, litterbugs, and lesbians, all of whom are only too well protected by graft. If you have a moment, I shall endeavor to discuss the crime problem with you, but don't make the mistake of bothering me." (1.14)
Ignatius has a point: Why does Mancuso bother him? Because he looks funny? If the law is applied justly, you shouldn't be subject to harassment by the police just because of how you look. Note, though, that Ignatius does want onanists to be harassed—and we know from the rest of the novel that Ignatius is an onanist himself (that is, he masturbates). Ignatius's hyperbolic intolerance of the modern world includes intolerance of himself, so in that sense there's perhaps some justice, or at least symmetry, in his being singled out.
He had told Mancuso that from now on he would be strictly responsible for bringing in suspicious character, that police headquarters had a costume wardrobe that would permit Mancuso to be a new character every day. Forlornly, Patrolman Mancuso had put on the tights before the sergeant, who had pushed him out of the precinct and told him to shape up or get off the force. (1.341)
The threat of the law throughout the novel is mostly used for bullying. The sergeant's bullying of Mancuso, therefore, just seems like an extension of police work in general. If the police are in the business of harassing oddballs, it makes sense that when there is an oddball policeman, his superiors will enthusiastically harass him.
"A thousand dollars? He will not get a cent. We shall have him prosecuted immediately. Contact our attorneys, Mother." (2.101)
The Reilly's have no attorneys, of course; Ignatius just likes to refer to them in hopes of bullying people into doing what he wants. If Ignatius were Boethius, The Consolation of Philosophy would be about how much trouble the king is going to get in for false imprisonment once Boethius talks to his lawyers.
"So we see that even when Fortuna spins us downward, the wheel sometimes halts for a moment and we find ourselves in a good, small cycle within the larger bad cycle. The universe, of course, is based upon the principle of the circle within the circle. At the moment, I am in an inner circle." (3.192)
Ignatius contemplates the workings of fate. If fate is random, it has little to do with justice. The vision of the universe as gears within gears, working sideways to justice, is not a bad image of the novel as a whole, where the intricate plot works away, and some people get lucky and some don't, with little relation, necessarily, to just desserts.
"Didn that lady say she call a po-lice if you give her trouble?"
"She got me there. " (6.10-11)
Burma Jones resignedly notes that Lana Lee, and the police, have "got" him. Many people in the novel are treated unjustly, but Jones, as an African-American, gets even less justice than most.
"I'm not gonna be robbed again," the old man said, spraying Ignatius with saliva. "That's all that happens to you in the hot dog trade. Hot dog vendors and gas station attendants always get it. Holdups, muggings. Nobody respects a hot dog vendor." (7.46)
Ignatius is trying to get away with eating hot dogs for free by basically stealing them. Mr. Clyde prevents this injustice by getting Ignatius to work for him—which allows Ignatius to eat even more hot dogs without paying for them. Mr. Clyde might have done better if he'd focused less on justice and more on simply cutting his losses. Incidentally, Mr. Clyde is right that no one in the book seems to respect hot dog vendors. This does seem unjust… but, like so much in the novel, there's not really any help for it.
"It wasn't your fault though, Miss Reilly. It's them police. They all a bunch of communiss." (8.170)
Communists in general were seen during the Cold War as quintessentially un-American, and, as such, were often persecuted by the police. Claude reaches an even higher level of Cold War paranoia by believing the police themselves are the Communists. While the specifics are garbled, his general point—that the police are not just—is more or less born out by the book.
"I recommend Batman especially, for he tends to transcend the abysmal society in which he found himself. His morality is rather rigid also. I rather respect Batman." (10.213)
Batman is one of the few figures that Ignatius approves of other than Boethius. He seems to like in particular his isolation and his harsh application of justice. You wonder if Ignatius occasionally sees himself in a Bat-costume, swinging hugely through the city like a bat-spackled blimp, confronting evil-doers and threatening to sue them.
A policeman was a policeman. It was always best to ignore them unless they bothered you. (12.210)
As a black man, Jones expects no justice from the police; the best he can hope for is to be overlooked when they start dispensing injustice. In this, he's cleverer than Lana Lee, who can't identify a policeman when he pops up in front of her. Maybe she's been doing too much reading.
"That Patrolman Mancusa say he appreciate showin him that cabinet. He say, 'Us mothers on the force need peoples like you, help us out.' He say, 'Peoples like you be helping me get ahead.' I say, 'Whoa! Be sure and tell that to your friend at the precinc, they don star snatchin my ass for vagran.' He say, 'I sure will.'" (13.115)
Jones is in good with the police essentially because he's done a personal favor for Mancuso and helped him get ahead. It's not about abstract rights—it's about one hand washing the other. If you get a policeman a promotion, the policeman won't arrest you for no reason. It's something, but it's definitely not justice.