Since the film Batman v Superman hasn’t been released yet, I feel like I can safely write a spoiler-free post for a change. From the title alone, we can infer that there will be some conflict between the two heroes.

Of course, it’s very standard comic book practice that before two heroes team up, they have to fight first before they realize they should work together. And we can be reasonably certain, given that DC is planning a “Justice League” project, that Batman and Superman will eventually join forces. But this upcoming film looks, from the trailer at least, like it will highlight the initial conflict. This is particularly interesting because the film is said to be influenced by the groundbreaking 1986 graphic novel The Dark Knight Returns by Frank Miller, Klaus Janson and Lynne Varley.

In Miller’s story, superheroes are outlawed, but Superman is permitted to keep working as an agent of the government. This brings him into conflict with Batman. The upcoming film will likely not be that explicitly close to the Miller story, but the basic issue remains: why shouldn’t we regard superheroes as vigilantes?

Of course, in literal terms, that’s exactly what they are: they take it upon themselves to fight crime independently of state-sanctioned law-enforcement agencies. In traditional liberal theory, we are supposed to have delegated the power to seek justice to the state. One reason for this is to make sure our personal biases don’t affect our judgment—we are generally not objective when our own interests are at stake. Another reason is to make sure that objective and fair procedures are followed: everyone treated equally, due process, and so on.

But wait, you may object, we do delegate these powers to the state, and yet people are not always treated equally, fair procedures are not always in place. So the ideal practices presupposed by the liberal tradition don’t always manifest. But they can fail in two distinct ways: 1) people who don’t deserve a punishment get one, and 2) people who deserve a punishment do not get one. Superheroes typically deal with the latter—they pursue villains who would otherwise escape justice because the police are incapable of handling them.

In a fictional world where some people have superpowers, this is perfectly easy to understand. Ordinary police are probably ill-equipped to handle a guy with four robotic arms, or who can turn into sand or molten steel, or who can control people with voice commands. But even in the real world, “can’t handle” can also refer to criminals who are politically well-connected or who exist in large enough numbers. So when the state’s police forces cannot (or will not) pursue justice, it’s not obvious that Bruce Wayne or Peter Parker or Jessica Jones are doing wrong by taking matters into their own hands.

Who could object to that?

Well, apparently Superman—both in Miller’s 1986 tale, and in the trailers for the upcoming film. He finds it disturbing that Batman operates on his own, not bound by procedural rules or due process rights. This is a legitimate concern.

In fiction, we can be sure that our protagonists are pursuing the actually guilty, but in the real world, this is part of the reason why we have due process rights—those accused are not always guilty. We tend to approve of superhero vigilantism because they only pursue the actually guilty. But other vigilantes, like the lynch mobs of the Jim Crow era, do not. It’s a virtue that comic books since Miller’s 1986 story (Alan Moore also played a substantial role in exploring this theme in the early ’80s) have taken these complexities seriously. It looks like the upcoming Batman v Superman film will do this as well.