Summary
Well, it finally happened: yourDungeons & Dragonsparty managed to fall a bit too far into the “evil” side of the alignment chart. As a responsible DM, you’ve arrested the group, but you’re not going to ignore due process entirely. Now the gang is about to have their day in court, but you’ve never run a trial before.
The stakes are high for your party, and trials are one time when you really shouldn’t improvise your way through the session. All that prepcan be intimidating, but there’s no need to stress yourself out. Here are a few helpful tips to make your trial go as smoothly as possible.

9Track What Characters Say
Anything You Say Can And Will Be Used Against You
In court, testimonies are often picked apart endlessly. The slightest inconsistency might be pointed to as a sign that something is amiss. That’s why real-life courtrooms typically have stenographers on staff to record everything said during a trial, so it pays to remind your players of this fact before the session begins.
A useful tool is to start recording your sessions as soon as your players get arrested. It’s best to get your players' out-of-character consent to this, but you don’t need to post the recordings online. Just keep them private as a reference tool if you need to remember how something was phrased.

8Evidence Is Key
The Proof Is In The Proof
Much of the advice that goes intocreating a murder mystery(or any mystery) also applies to trials. Keep track of any clues that are left behind at the scene of the crime. Documents such as receipts, letters, and other minutiae your players might usually ignore could be the key to getting a favorable ruling from the judge.
However, don’t forget the tools Fifth Edition gives your players if they want to take part in some foul play of their own. Tool kits are an underutilized part of the character sheet, and the best part about disguise and forgery kits is their inability to be discovered with spells like Detect Magic.

7Consider Social Combat Rules
Fifth Edition Isn’t Normally Built For This
Unlike other systems such as World of Darkness, Dungeons & Dragons doesn’t exactly have a robust set of rules for intense social scenes. This can put social roleplay in a weird state of limbo where dice rolls don’t feel integrated into the story, but pure roleplay doesn’t feel crunchy enough.
There are rules for more nuanced social intrigue in the Dungeon Master’s Guide, but if they’re not to your liking, you have other options. Trials are one of the best situations for social combat rules, so check the Dungeon Master’s Guild or D&D Beyond for some homebrew rules if you’re so inclined.

6Know The Law
And Know The Exact Wording, Too
Your players might make some assumptions about how the law worksin your setting(murder is probably bad), but those assumptions are just that: assumptions. Maybe necromancy is legal if the deceased gives prior consent. Perhaps murder is a lesser crime if the guy you killed gets resurrected afterward.
Also, consider the exact text of the law or laws being violated. In real life, lawyers and judges argue over the meaning and possible interpretations of a statute’s text all the time. A single word or line of text could be the key to your PCs being acquitted or found guilty of a lesser crime.

It doesn’t have to be too complicated: giving your PCs a handout with some relevant laws is a helpful gesture. Waterdeep Dragon Heist is an official adventure that does this, if you need examples.
5Know The Legal Systems
You May Want To Do Your Research
In the United States, the accused is presumed innocent until proven guilty, but this isn’t the case every time or place. Deciding on the finer points of your setting’s legal system will help flesh out how your sessions are run. Can someone appeal a ruling they find unfavorable to a higher court, or do you only get one shot? Is trial by combat a thing, or are people less bloodthirsty?
Also, consider who the legal system applies to. Most players and DMs limit this to humanoids, but in real life, it wasn’t uncommon for animals to be arrested and put on trial during the medieval and Renaissance eras. It’s not too weird to consider most of the Monster Manual subject to the laws of the land.

4Figure Out What Skill Checks Will Accomplish
Remember: Persuasion Is Not Mind Control
Dungeons & Dragons is fundamentally a game about going into dungeons, killing monsters, and taking their stuff. While the game has evolved beyond this premise over the years, the fact of the matter is that the Fifth Edition character sheet doesn’t reflect this. Combat skills and spells are still overemphasized.
Consequently, your players may have unrealistic expectations of what Insight, Deception, Persuasion, and Intimidation can accomplish. Make sure you clearly communicate what your players can and can’t do. A natural 20 on a Persuasion roll is probably not going to get them everything they want, but it will get them the best outcome that’s realistically possible.

3Prepare Your Spells
Magic Is Cool, Too
There area few different spellsthat can be used in trials. In real life, people are usually required to give a sworn statement that everything they say is true to the best of their knowledge. you’re able to accomplish this in D&D by having characters willingly subject themselves to a Zone of Truth.
Speak With Dead is another spell that NPCs might use before or during the trial. It’s kind of hard to deny that you murdered someone when the deceased outright says you did the deed, so it’s only natural to assume this is going to be the first line of questioning for any situation that resulted in someone’s death.

2Flesh Out NPCs
Don’t Be Afraid Of Drama
Decide on key NPC traits, backstories, and motivations early. Is the prosecution a cynical veteran or a rookie out to prove themselves? Is the judge a wise individual who applies the law fairly, or are they a corrupt magistrate who can dish out any verdict you want for the right price? Figuring this out helps you plan the flow of the trial and possible NPC reactions to player shenanigans.
Most of the advice you just read applies to humanoids, but note that you should pay special attention to trials that involve devils or fey in any way. Fey are likely to have weird, whimsical interpretations of just about everything, but you’ll need to work overtime on prep work if you include any devils.

1Figure Out The Stakes
And Figure Out The Consequences Of Failure
Have some forethought when deciding on sentences for characters found guilty. Punishments that remove a character from the game (such as execution or long prison sentences with no hope of a jailbreak) should be discussed beforehand and reserved for terrible decisions that happen alongside terrible dice rolls. Exile or other punishments that trigger quests can keep the game enjoyable to play.
This advice doesn’t apply to NPCs. Publicly execute NPCs all you want.
If your party behaved like horrible chaos gremlinsbeforegetting arrested but performed well at the trial, you have some options. It’s common in real life for defense attorneys to try to get their clients a lighter sentence or convicted of a lesser crime. Community service is a much less dire sentence than life in prison.