To the Courts, Opening Statement

I decided, when I started this little topic, that I’d be developing an adventure as we went along, so you folks could see how all of this comes together.

Alright. So let’s assume that our end target is to have the PCs have to ‘rescue’ one of their allies, the Paladin Alex Blackhart from the prisons of his liege lord, the Good King Amplestan. Amplestan is himself, an ally of the party. He and Blackhart are good friends, both lawful good folks. Blackhart though has been accused of murdering a Duke, destroying the village of Con and conducting an evil ritual (using the destruction of Con as its fuel) to summon a demon who is currently rampaging through the crappier parts of the capital.  

Blackhart abjectly refuses to break out of prison. He won’t countenance anyone just busting in and ripping him out. And he doesn’t want to see honest guards and honest soldiers harmed. Traits which probably made him a pal of the party before, well, this.

He also says he’s innocent. Unfortunately for him, there’s a pile of evidence against this. Eye witnesses, physical evidence, and of course, the demon. Also, divinations have come back claiming that he’s guilty as sin, with other divinations saying he isn’t, but the weight of evidence is going to have Blackhart walking up the pathway to the gallows. Something which the King would rather see not happen, given the demon, and given his relationship with the man, but the King is a Good King ™ and therefore can’t be seen to play favorites, nor to treat the law as something he arbitrarily uses by wiping the issue away or issuing a pardon (which would still require exile), so his proverbial hands are tied.

So this above exemplifies some of the requirements I see in the Legal based mystery adventure.

1. The Innocent Party. Here, Paladin Blackhart. Note, that ‘The Innocent Party’ does not always need to be strictly Innocent, but should be Innocent of the crime that’s got him in trouble necessitating action on the part of the party. If he’s not, that can be used for intrigue too, as the party makes the terrible discovery of their friend, ally, or whoever actually being guilty, but if you do that make sure there’s something fulfilling about the adventure, or they’ll just get pissed at the shaggy dog ride.
2.  The Necessity: Blackhart refuses to get broken out, or do it himself, and the King can’t just solve the problem. The necessity’s function is to make it so that violence isn’t the easiest solution to the problem. 
   If the Kobold King was holding Bob the Gnome in his jail for the crime of aggressive Gnomery and the punishment was death, the party might decide (rightly) to just kick the Kobold King’s ass. If it’s something like the King of Neutralvania is holding someone for theft, the party might still blast their way in, even though Neutralvania has massive armies, but might choose not to because the consequences are bad.
   
   
   The PCs could always try breaking Blackhart out, maybe even convincing him to flee without his honor intact. But that’s not ideal. The Necessity is basically ‘why we’re having a court adventure’ so well, it has to be tailored for each situation. Just watch out for weak sauce reasons. If the player’s first thought is ‘how do we get him off of this bullshit charge’ that’s good, if they think ‘that’s dumb, I’m gonna break faces’ that’s usually bad.
3.  The Foe. AKA. The Evidence.
   The enemy here is the evidence. The facts that are holding our Innocent party prisoner. They’re like midbosses in the dungeon, they have to be tracked down and killed. Towards this end, they..

• Should always be clearly defined.
• Should always be clearly enumerated from the beginning.
• Should be tied to appropriate hooks. 

Notice I didn't detail who did the crimes, or what's going on, or how to solve this. That's because that comes later. Once you the DM decide what the adventure and the initial set of complications are going to be, then you have to go back, and well, figure that stuff out.

So, the next step is well...

The Timeline.