Unreasonable Searches and Seizures

Oh my god. YOU'RE RIGHT ! I think that's the first time a movie isn't a 100% depiction of reality !! So.. you're the fun one at parties. Huh?

I mean, this was literally a primary plot point of The Dark Knight.

Err. Batman is not working on behalf of the State; however, the local government benefits on behalf of Batman's actions... for the most part.

Batman is equivalent to ANTIFA, all dressed clad in black. Justice system is pro-crime hence why if he is ever arrested he's bailed out fast by secret AG Gordon.

Not clear on the concept of comic book super heroes, are you?

The whole point of vigilante justice is that they operate outside the parameters of the law. In one of the old comics a flashback shows Bruce Wayne in a law class where there's a caselaw discussion with an unfair outcome and Bruce asks of the professor "Is that justice" and his professor responds "No Mr. Wayne, that's the law".

Rather than whether or not Batman believes in due process a better question would be should any evidence the police receive due to the Batman's illegal tactics be admissible in a court of law? In The Dark Knight it's said that the police department's official position is to arrest the vigilante known as Batman. But with a giant bat signal on the roof of police headquarters it would be fair to argue that he is working as a deputy of the police department and should be held to the same restrictions. However Gotham is usually portrayed as a different type of place in need of a different type of justice where all the players know they live in a world where the normal rules don't apply. In the end trying to make real world sense of a comic book movie is very much a futile effort.