Anthony Stokes has a few suggestions on how Warner Bros. could make a Justice League movie work....
The very first thing Warner Bros. needs to worry about is how to introduce the roster. The original plan was to use Justice League as a way to create audience interest in these characters and then have them spin-off into individual movies. This is a horrible idea and clearly just a way to fast-track a franchise. The right way to do it is to release individual movies featuring the more popular characters in the lead up to Justice League. Aquaman, Cyborg and Martian Manhunter do not need solo films - treat them like Hawkeye and Black Widow in The Avengers and use them sparingly, or even just focus on the other members before bringing them in later and fully fleshing them out.
Then there's the question of what to do with The Dark Knight. My biggest concern is not only why would Batman join a group of superheroes, but also nothing in the entire Batman film universe to suggest he would stand a chance against any members of the Justice League. The Flash or Superman could kill him instantly - what purpose would Batman serve next to a man who can fly at the speed of sound? Batman needs to be rebooted before Justice League, or at least given another movie with a brand new tone. He's an essential piece of the team, but currently he wouldn't fit in thematically. The new Batman should be stronger and more competent to be able to keep up with the rest of the League. The Batman from the comics is not only a genius, but he always has a trick up his sleeve, and is extremely cunning and cold in battle. A rebooted Batman needs to play up the more fantastic elements and even make him a little psychologically compromised to give him an edge over the rest of the the team. If they go this route, it's probably better to do a World's Finest movie and use that to build up to Justice League.
My final piece of advice to Warner Bros. would be to slow down and really take a look at what they've done right and what they've done wrong. Not only look to themselves, but look to Marvel. Everything in the Marvel Cinematic Universe feels thought-out and natural, while every move on Warner Bros.' part feels rushed and reeks of desperation. Stop trying to build Rome in a day and focus on making good quality films and the money will come in.
Anthony Stokes is a blogger and independent filmmaker.