You've been making film for Hollywood for a while - what made you want to do something more stripped down?
"I just wanted to have some freedom to make a movie the way I see it and not be restrained and work with actors I wanted to work with without having someone dictate who has to be in your film."
There are elements in this film that you wouldn't expect from a big Hollywood production - do you think the film would have been compromised if you had done it that way?
"Yeah. If it would have been within the studio system there's no question. That Richard Gere getting a blow job scene wouldn't have gone in the movie, everybody would have lived happily ever after - that's the reason I did it. I didn't want to compromise."
That Richard Gere scene wasn't in Pretty Woman!
"That's why I wanted him in the movie, to be something different than him and let him do some real acting as opposed to posing him."
Was it daunting filming in the Brooklyn projects?
"For me I was comfortable there. I did the same thing on Training Day, I love being on the streets with the people. That's what gets me going every day - it's like my coffee. Once I step out on the street I feel more creative and I can breathe and see it in front of me. Again it helps with the actors and everyone. It's the truth right in front of you so if there's something phoney about you or your actors it's pretty clear. I like to surround [actors] with people who live that lifestyle and where it really happens. The actors can look around and see when they're faking it themselves because there's a real guy who does this for a living right next to you. If you're not being true it's pretty clear."
Are you a fan of The Wire, there's a couple of actors from that show in the film?
"I am a fan of The Wire. I didn't watch The Wire as much as people think I did but I like The Wire a lot and I did see it. Michael K. Williams himself is from Brooklyn so I was trying to cast it as authentic as I could. Also I thought it was such a good show that never got any real attention in the States - they ignored it with the awards and everything. I thought that everyone did such a great job on the show they deserved a chance to be seen on the big screen as well."
Do you think Training Day, The Wire and Brooklyn's Finest are interlinked in some way?
"Absolutely, it's the streets. The code of the streets, the way it works, the way cops behave in that environment. What people don't realise is they eventually become part of the neighbourhood and they become subject to the same rules of the street and the same code of the street so their behaviour dictates that. It's a great line."
Are you ever tempted to go back to directing big Hollywood blockbusters?
"I'd like to. King Arthur was a great experience for me and I learned some things not to do! I learned a lot about the difficulties of doing a big movie like that and the expectations of it. I'd like to do it again with a little more business savvy, creatively. It's a great experience and I want to do it again. There's some things on the table for me but I'm a little hesitant."
Is your Pablo Escobar biopic still on the cards?
"Yeah, I just got another draft in and I'm going to sit and read it this weekend. I'm working hard on it, I've been working on the script for a while and just didn't want to get it wrong. I think it's an important story of what was happening at that time and with him. We want to get it right, or as close as we can."
Does it span the whole of his life or focus on a narrower timespan?
"It focuses on his whole life, from when he was 12. [It starts with] him and his brother walking home from school."
Would you cast that with an unknown or go for someone like Javier Bardem?
"That's who I would like, I would like Javier. I'd like Javier and Benicio [del Toro] to play brothers, to play Roberto and Pablo."
Brooklyn's Finest opens in the UK on Wednesday.