I'm not a lawyer, but I've watched an annoying number of court things and served on a few federal juries so I do have some perspective on how things flow. Some random bits:
1. Courthouses (at least, any courthouse that deals with real crimes) have security checkpoints at all entrances and armed guards inside. It's super-rare that someone manages to shoot a prisoner in the courtroom anymore, unless they manage to overpower one of said guards (of which there are many).
2. Trials take forever. A murder trial can easily drag on one, two, or even more years.
3. Most of the time, a murder verdict requires a unanimous vote from the jury. If the jury cannot reach a unanimous decision, the trial is called a "mistrial" and the prosecution can choose to retry it, which starts most of it over from the beginning.
4. The jury isn't asked to determine whether someone is guilty of "murder" or whatever. Instead, the jury is presented with the text of a very specific charge "that this person killed this person with this set of conditions" and must determine whether that person did so beyond any reasonable doubt. "Any" and "reasonable" are the keys there (and judges will belabor them quite a lot in the jury instructions). It's quite possible for someone to be relatively innocent in what they did, but have their behavior still fit the criteria of a serious charge.
5. For every minute of trial, there's probably at least an hour of pre-trial legal wrangling. It starts from the very first and just keeps going. Where will the trial be held? What evidence is admissible? What witnesses are permitted?
6. The Fifth Amendment to the US Constitution gives a person a right to remain silent in criminal proceedings. This generally means that the defendant does not "take the stand" (to testify). It is almost always a bad idea.
7. The jury pool is selected at random from a big group that is currently "on duty". Each side will interview this group (usually all at once, and then directing specific questions at individuals) and reject the ones they really don't want. Rejects are limited, though, and it can be impossible to get a completely unbiased jury, especially in the matter of highly public trials. It's also quite possible that, in the months leading up to the trial, the prosecution or defense will make public statements in order to push this bias in their favor.
8. The defendant generally has to wait in jail for the trial, unless they can make themselves not a flight risk in some manner. Generally, this is done by posting a bond with the court as insurance that they will return for trial (though the amounts required for murder trials are very high). The value is set such that it's believe the person won't flee and lose the money. Given the resources of a Lantern this is kind of a difficult prospect and would likely take a personal guarantee from one or more JL members or something.
9. As for the actual trial, the prosecution goes, then the defense. Both sides make an opening statement at the start of the trial and a closing statement at the end. Then the jury deliberates and returns a verdict.
10. For each witness, the "side" that calls them asks questions, then the other side gets to ask them questions (cross-examination). Finally, the original side has a limited ability to ask final questions (redirect) related to the questions and answers from the cross-examination.
11. Self defense is a defense that does not deny the facts of the matter, but argues that they were legal because the defendant had a reasonable fear for his life or the life of others. Missouri is a "obligation to flee" state that says that the defender must first attempt to flee the situation before resorting to deadly force, but I don't think that'll apply in this case.
Err... that may or may not help. Anyway, love the story
