Todd Phillips spent a full year convincing Warner Bros to say yes to R-rated 'Joker'

"Joker" director Todd Phillips has revealed he spent an entire year trying to convince Warner Bros to let him make a violent and edgy film on the iconic DC villain.

The film, which earned an expected R-rating by MPAA for "strong bloody violence, disturbing behaviour, language, and brief sexual images", is an origin story of the Clown Prince of Crime, with Joaquin Phoenix playing the title role.

Phillips said it was "a year-long process" from the time the script was completed "just to get the new people on board with this vision".

"There were emails about: 'You realise we sell Joker pajamas at Target'. There were a zillion hurdles, and you just sort of had to navigate those one at a time...

"At the time I would curse them in my head every day. But then I have to put it in perspective and go, 'They're pretty bold that they did this'," the filmmaker told the Los Angeles Times.

He said while the audiences may be acquainted with R-rated films thanks to "Deadpool" series, "Joker" is a different animal.

Phillips drew his references from matter-of-fact R-rated adult dramas such as "Taxi Driver" and "One Flew Over the Cuckoo's Nest, among others.

He said, "The movies that I grew up loving, these character studies from the '70s, you couldn't get those movies made in this climate. I said to myself, 'What if you did a movie in that vein, but made it about (comic book) characters?'"