The Statement For The Prosecution:
I'm probably not the best person to make this statement because I don't think the film is all that bad. Mainly it suffers from not being the comic, and the comic having a particularly rabid fanbase (I am one of them, even if Dredd isn't my favourite 2000AD character).
A lot of the backlash could have been avoided if they hadn't broken the golden rule of Judge Dredd, which is 'never show his face'.
They also made Hershey far too squishy.
On a personal note,
I could have done without them killing of McGruder, even if I was really happy to see someone who was recognisably McGruder appear. Actually, in keeping with the scene that's the topic of the scene in question, McGruder is the only person to ever return from the Long Walk, when she gets called back as the only person with enough experience to be Chief Judge after Chief Judge Cal's reign. Being as she is awesome, the minute her reign is up, she goes back on the Long Walk.
It's little details like that that make me think that some love and attention did go into making this. Most of the problem is that, with the exception of the food droid bit (quote - "Be kind and peaceful to each other. Eat recycled food. It's good for the environment and okay for you.") the film forgets that Dredd is a satire. I try not to hold this against the film, since the comic sometimes forgets that too, but it's also part of the reason it got a rough ride from the 2000AD fans.
Rico and Dredd are supposed to be clones. And I get that they cast Armand Assante because he looks like he could be distantly related to Sylvester Stallone without making it obvious what the twist is. But neither of them look particularly like Max von Sydow, who they are supposed to be clones of. Imagine how much more believable the plot would have been had you not seen Dredd's face.
The Scene Itself:
Which I again cannot get a clip of, mostly because people prefer to clip the 'I am the law' scene.
I can, however, get you the dialogue, care of IMDB:
Judge Dredd: [During an "Ethics" class, Dredd fires continuously at a "Judge" helmet and armor] ... The Judge's standard-issue helmet and body armor. Yours, when you graduate. Lawgiver-2 standard-issue sidearm, with 20 interchangeable rounds and voice-activated round system.
[to the Lawgiver]
Judge Dredd: Signal flare.
[fires a signal flare into the wall]
Judge Dredd: Yours, IF you graduate.
[walks over to a futuristic motorcycle]
Judge Dredd: Lawmaster, with rapid-firing cannons and a range of 500 kilometers.
[turns it on; it malfunctions]
Judge Dredd: Yours... if you can ever get it to work.
[cadets laugh]
Judge Dredd: All the things you see are toys; at the end of the day, when you're alone in the dark, the only thing that matters is this...
[holds up the Book of the Law]
Judge Dredd: ...the Law.
[slams the Book onto the table]
Judge Dredd: You WILL be alone. Upon retirement, you will take the Long Walk... which every Judge takes, outside these city walls, into the Cursed Earth. There you will remain for the last of your days, alone and carrying the Law. Class dismissed.
Why the Scene is so Good:
This scene is the closest the film gets to explaining the price of being a Judge. The Long Walk is how Mega City One deals with the 'what do we do with these over-trained violent people when we're done with them?' There is no retirement for Judges, after 25/30 years of service, they get sent out into the Cursed Earth, a radioactive post-apocalyptic wasteland to bring law unto the lawless, until they die. And that's assuming they reach retirement age, which very few of them do.
They give up everything (because they're basically forbidden from romance, children and pretty much anything that resembles a personal life - see also why Hershey should be less squishy) for very little in return. And the Academy is the point of no return. If you graduate, you're a Judge for life, and I think Dredd wants the cadets to know that, and what they're signing up for.
Secondly, once you know that, it helps you understand why Dredd feels so betrayed by any Judge, never mind one that he considers a brother, breaking the law. It's spitting in the face of the sacrifices all the other Judges make.
Thirdly, much though he gets mocked (and, spoiler, at least two more of his films will appear in this list) Sly Stallone can act, when the script plays to his strengths, and he's very good in this scene. It's the first time Dredd is given any humanity (the joke about Lawmaster), rather than sarcasm and bile, and he gets to be The Voice of The Law (capitals utterly required), again, rather than sarcasm and bile and having to be the front man for the incredibly irrational law of Mega City One.