Prince of the City (1981)
What a great heartbreaking film by Sidney Lumet. After the movie I read Roger Ebert's (RIP) review of the film and he mentions....
"He will not rat on his partners. This is his bottom line. He will talk to investigators about all the other guys he knows things about. He will talk about how narcotics cops get involved in the narcotics traffic, how they buy information with drugs, how they string out addicts and use them as informers, how they keep some of the money and some of the drugs after big busts. He will tell what he knows about how the other cops do these things. But he will not talk about his partners in his own unit. This is his code, and, of course, he is going to have to break it."
Wow just wow. Heartbreaking