More specifically, I'd like to address a comment made by creator Marc Andreyko on the Geoff Johns boards. It's not unlike some comments he made in response to criticisms elsewhere. (And I should note that Mr. Andreyko has shown himself to be very open and willing to talk with fans, including critics such as myself, which is always nice to see in a pro, and I applaud him for it.) But this particular quote seems to best encapsulate a common response to legal critiques of recent issues:
"take into account that because this is a super-hero world, that trial laws are different."
In general, I agree with that sentiment. There are certain conceits in the superhero genre that would all but force certain changes in a trial setting. The last Astro City mini-series showed what some of those effects could be, for example. Bob Ingersoll used to address the point regularly. Unfortunately, nothing about superheroes and supervillains would result in the discrepencies we've seen in Manhunter itself.
Perhaps the three biggest conceits of the superhero genre are: 1) Fantastic powers, 2) Secret Identities, and 3) Vigilantism. Each of these can have their own effect on courtroom law and procedure.
I've touched on the issue of powers before, particularly in my Ultimates analysis. If a party's powers might prove risky in a courtroom, certain precautions could be expected that a regular court wouldn't allow. If a teleporter is on trial, it's natural to assume that he'd be somehow restrained from disappearing. The dangers of a witness or party having mind-control powers, and influencing jurors or witnesses, might have to be addressed somehow.
An issue of She-Hulk made a point out of the secret identity problem: if Spider-Man is called as a witness, how can it be verified that it's the real Spider-Man? A superhero universe would have different means of determining witness identities for masked individuals, and they would have some sort of end-run around the Constitutional requirement of facing their accuser.
I think an issue of Tangled Web took a look at the vigilantism problem from a police perspective. Spider-Man may catch criminals and leave them for the cops, but what proof is there that they did what they did? Are superheroes considered gov't agents for the purposes of determing the legality of searches and confessions? The DCU might have different rules on the subject than we do.
The trouble with applying this "superhero world" rationale to Manhunter is that none of its errors can be explained away because of the existence of superheroes. The rules about character evidence aren't going to change. The rules about what is relevant and irrelevant testimony aren't going to change. Prosecutors are still going to have to prove their case beyond a reasonable doubt, and they need to produce actual evidence to do that. (If anyone would like to argue that such changes would be natural consequences of superheroes, I'd love to hear the reasons.)
Andreyko did bring up one problem that a DCU court would have to address, in the form of the murder victim having a secret identity. Unfortunately, as I explained before, the way it played out was almost certainly not the way a DCU court would handle it.
Also as pointed out previously, if Sands is still a metahuman, then the court might permit the tube (something they'd never do in real life). Since I'm pretty sure he's not, then it's out of place.
Maybe the court would allow for the defendant to be called a "Thief" in court, and not deem that prejudicial. That might fly. For a real-world parallel to that, let's wait and see if the prosecution in the BTK killer case (where the defendant coined his own acronym) is allowed to call the defendant "BTK" during trial.
And while I'm on the subject of Manhunter and Mr. Andreyko, I feel obliged to share his plea that people support the title. The book may have its share of legal problems, but it's garnered quite a lot of praise for its other strengths. If it can attract a strong enough audience to convince DC to stick with it, then maybe Mr. Andreyko will be able to explore some of the real superhero legal quirks down the line.