Bad Lieutenant

Bad Lieutenant is a film made in 1992 by Abel Ferrara, concerning a nameless New York police lieutenant (played by Harvey Keitel) as he went about his daily business of solving homicides while simultaneously indulging in his drug habits and prostitution and worrying about how to pay off his baseball gambling debts, all the while using his position as a weapon to get away with everything. During the investigation of a nun's rape, the Lieutenant begins to reflect on his lifestyle, wondering if he can change it.

The film inspired Bad Lieutenant: Port of Call New Orleans, a movie that features a similar main character, yet is still quite different.

Tropes used in Bad Lieutenant include:

The Atoner: The Lieutenant is gradually revealed as this.
Author Appeal: the Lieutenant sometimes visits the apartment of a thin girl who shoots heroin. She was played by Zoe Lund (née Tamerlis), who was the cowriter of the screenplay, and was a heroin advocate. She is also given writing credit on "Port of Call New Orleans", although by that time she was already deceased. From heroin.
Creator Cameo: Zoe Lund. She had previously worked with director Ferrara, having played the titular role in Ms.45.
Dirty Cop: And how.
Hookers and Blow: There's several scenes of the Lieutenant getting strung out with a couple of prostitutes. It's a lot more sleazy and grimy than the trope is usually presented, however. In the scene with Zoe Lund, that's real Heroin being injected into her.
Karma Houdini: The nun's rapists. Even considering the fact that the nun forgives them, the Lieutenant smoking drugs with them and then putting them on a bus for parts unknown doesn't seem like that much of a punishment.
- And the Lieutenant gave them the cigar box with three grand in it.
Leave the Camera Running: The final scene keeps going after the main event occurs.
Male Frontal Nudity
Manly Tears
No Name Given: The Lieutenant.
Rape as Drama: The nun.
Redemption Equals Death: The Lieutenant.