Judge Dredd is based on one of the most popular characters from the UK's 2000 AD comics. It is set in the 22nd Century, when most of the Earth has been turned into a desolate wasteland known as the "Cursed Earth" and most humans live in highly concentrated cities, walled off from the rest of the world. Society is fairly anarchic, except there for a class of humans, known as "judges", who act as cop, judge, jury and executioner all rolled into one. Sylvester Stallone is the titular judge. He's notorious among the other judges, the general citizenry and the other judges for upholding the law in a harsh way. The film primarily tells the story arc from the comics known as "The Return of Rico", and concerns a plot to get Dredd into trouble while overthrowing what's left of the existing "order".
This is a great action/sci-fi film with a tone reminiscent of Demolition Man (1993), Total Recall (1990), The Fifth Element (1997), Blade Runner (1982) and similar films. If you like Stallone, gloomy futuristic production design and/or intense action films, Judge Dredd should be a rewarding experience for you, as long as you're not a purist who is coming to the film by way of an intricate familiarity with the 2000 AD comics.
The source material caused a slight problem for me, too, but not because I'm a purist. Rather, Judge Dredd suffers a bit from a flaw that plagues many films based on comic books--writers Michael De Luca, William Wisher Jr. and Steven E. de Souza had an extensive, pre-existent mythology (as is necessary when creating a complete, new world) on which to build their work, and they tried to incorporate a bit too much of it. Because of this, we're introduced to a large cast of characters fulfilling functions that we're not familiar with (in the details, at least), and we're regularly faced with new lingo, new cultural concepts, new technology, and so on, often with just a couple lines of dialogue. If you want to understand the details, you really have to pay close attention. But on the other hand, the general arc of the story is relatively simple, and you don't have to know every detail to enjoy it.
Given the disposition that Stallone has as Judge Dredd in the film, he may as well have walked out of Kurt Wimmer's film Equilibrium (2002). Dredd initially goes about his business almost robotically; he only cares about enforcing the law. When he's recruited by a higher-up, Chief Justice Fargo (Max von Sydow), to teach ethics (which is quite an ironic idea when you see Dredd's behavior in the opening scene), he tells the students that being a judge basically means giving up one's life to the law. He says that one cannot have friends, for example--never mind that other judges, like Judge Hershey (Diane Lane) try to have social lives outside of work. Dredd later tells Hershey that he did have a friend at one point, but he had to judge him. Sending a friend to prison or killing him (we're not told exactly how Dredd judged him, although we find out later) isn't exactly the best way to encourage a healthy social life.
So the subtext of the story, and Dredd's character arc, becomes that through a number of hardships, he finally learns something about ethics for himself--just in time to deal with a potentially shattering bit of information about his personal identity. He ends up accompanied by a man, Herman Ferguson (Rob Schneider, in a role meant primarily as comic relief, although more generously, he's an ironic emotional facilitator), whom he had just judged harshly, even though Ferguson wasn't really doing anything wrong on his first day out of prison. Together they have to go to a figurative hell (The Cursed Earth) to deal with figurative "demons" (a famed band of rogue cannibals who live in the tough environment) and back again to reach their fulfillment.
Like many recent sci-fi stories set in the future, Judge Dredd has a pessimistic view of where technology and social conventions are leading humans. As the story has it, at one point, we had built massive, relatively unstoppable robot warriors, and one of the highlights of the film is when the villain finds one and puts it back into service. It's as much fun to watch the gadgetry as it is to watch the action sequences, and the computer generated "landscapes" throughout the film are spellbinding, with their sly jabs at various changes and similarities to present locations and cultures. The whole concept of the judges and their hierarchical structure is fascinating, even if some apparent inconsistencies (such as why judges are not summarily dealt with in the same manner that other citizens are) are never explained in the film.
The performances are good, even if a few actors barely get enough screen time (like Lane and Joan Chen, who plays semi-villain Ilsa), and the premise is captivating. It's too bad this film gets unduly knocked by purists and those misguidedly looking for detail realism in the genre. Judge Dredd is severely underrated on IMDb. It deserves a first look or a second chance.