Based on the storyline from the Superman/Batman comic book, the film poses that a large chunk of the planet Krypton is on a direct-heading for earth, which seems to be all of the ammunition that Luthor needs to bring the Man of Steel down once and for all.
“To a large degree, this is Luthor’s story,” offers writer Stan Berkowitz, who adapted the comic. “When you first meet him, it seems that he’s been reformed and is making a real difference in America. It’s just this meteor that screws everything up, and Luthor’s hubris to not want to work with Superman. That’s his fatal flaw in this story. He’s the science nerd who won’t accept the help of the star athlete and he just goes crazy.”
Jeph Loeb, who had been writing the Superman comic before launching Superman/Batman, explains that his goal with “Public Enemies” was to deal with the fact that he had made Luthor president. “It was time for Luthor to go,” he says matter of factly. “So that was the big story. At the time, the whole idea was to act as a metaphor for a country insisting there were weapons of mass destruction in another country and then invading that country. Which we all know would be fiction. This was another fictional account of what would happen if the President of the United States decided that something was an imminent threat and would then make sure that people, who were actually innocent, would be hunted down and put into some kind of prison situation. It was a great way to kick off the series, which was to have Luthor offer a billion dollar ransom for the capture of Superman, which meant every villain in the world would come out after him and that anyone who helped him would be convicted as well, which put Batman on the outside — which is where he wanted to be anyway.”
The challenge of adaptation, says Berkowitz, was to make it believable that the public would turn against Superman. This was accomplished when it seems that Superman has killed one of his enemies, Metallo, and Luthor makes the claim that the closer this Kryptonite meteor gets to earth, the more impact its radiation will have on Superman, causing him to act irrationally. The general public then becomes paranoid about Superman, making it all the more believable.”
Initially President Luthor offers a bounty for Superman’s capture, resulting in numerous villains going out after him. Then he turns to America’s superheroes and, issuing an executive order, has them (including Hawkman and Captain Marvel) try to bring Superman and Batman in, resulting in an incredible super powered smack down that spans a decent part of the film’s running time.