As is the case with such matters, both of the Nolan brothers have been coy about their involvement, but not necessarily quite. When asked about the film, Jonathan Nolan hinted that we will see a completely different take on Batman in this DC Comics ensemble, but he'll still be the black sheep of the family, so to speak.
"I'm incredibly excited [about Justice League]. I was a big Batman fan when I was a kid. In fact he was the only comic-book character I really liked. I went through a brief spell where I was reading Captain Britain, because I was an English kid living in the States, and Wolverine for 30 seconds, Spider-Man too, but really Batman was the one. And I love that there are different versions of the character. I love that in the context of Justice League, he's kind of the black sheep of that family."
The writer/producer than revealed which characters he never thought could exist in the Nolan universe version of the DC Comics world. He also explained the Robin gag at the end of The Dark Knight Rises.
"Clayface or, indeed, The Penguin. Part of what's compelling about Chris's take is the naturalism of it and I think that's one of the things I loved about the Frank Miller comic books was that they were sort of urban, gritty vigilante stories first and foremost. So everything had to stick within that universe. It's hard to imagine [in these movies] any of the rogue's gallery characters who have sort of a more supernatural or science-fiction bent to them. And I think that's one of the aspects of Batman which are fascinating: in 70 years, the character has been sort of fully laundered. Because of writers and artists having every month coming up with a different story to tell with this character, there are often different genre aspects to it. You have your science-fictions, you've had fantasy elements along the way, horror, camp comedy... I mean there are so many different versions.
It is a little hard to imagine Robin working in that universe, so the idea had to be limited to that gag at the end. But Joseph Gordon-Levitt's character is very important to the story. In any movie you need a character looking at proceedings the way you see them, and Joseph Gordon-Levitt's character is that character for this film. One of my favorite scenes is when John tells Bruce how he knew he was Batman. It's like that scene in The Prestige where the little kid sees through Christian Bale's trick. Little kids, they don't have any illusions, they just see the truth of the situation. I feel there's a kind of spiritual connection between the two movies there."