Trials: Share What You Know/

I researched Celtic culture (mostly for the clothing for my own personal uses) and found their laws to be very unique and interesting. It's a bit advanced for the world, but maybe it would work in your story.

The Celts didn't have prison. Everything was settled with fines. I know I've mentioned this stuff here before but I'll be brief this time. If you killed a neighbor's goat, you had to pay for the goat and the loss of future kids, milk, etc. If you killed a nobleman's goat, the fine was less severe than killing a poor man's goat, where the goat meant more to him. It seems basic and unrelated to war, but the laws encompassed many things, some as trivial as right of way upon two men meeting on a bridge (the poor man with his cart would go before a nobleman on his horse). Also, fines settled disputes like "My neighbor stole two of my cows and killed my uncle in their raid." Fines covered everything and for good reason...without money, a man couldn't have a wife, children, or claim to the clan's community land (which traded hands every year or two from family to family, so everyone had better or worse land and no one got an unfair shake). Poverty was punishment. People were exiled from their clans if they disgraced their names.

In the Plymouth colonies, fines were used, but also public degradation (stocks or prison). Two young lovers who were found fornicating would be given fines and whipped (if they refused to marry after the incident..they got away without the whipping if they agreed to marry). These laws encompassed mostly religious transgressions (traveling on Sunday, missing church, denying the scriptures) but also social ones (getting drunk, lying in public, or gambling with dice or cards). And a few carried death sentences (willful burning of ships or houses, willingly committing murder).

When a culture decides what is a crime, it must fit with the ideals of the culture. Also, the penalty has to be pertinent to the culture. The Celts who had no prisons couldn't give jail time, and even Plymouth Colony didn't have a prison, just a lock-up for the occasional wrongdoer to spend a couple days thinking about what they had done.

Some punishments from the ickier times in Europe have captured my imagination and while I'm partially disgusted by the brutality of our ancestors, I find the ingenuity of some torture conducted in public rather fascinating. Sorry if that sounds morbid. I wouldn't at all like to live at a time when corporal punishment was accepted, but some aspects of the great fear one must have suffered, being led to a Catherine Wheel or even a gallows--because the sharp drop wasn't invented until late in the game (1783)...I mean, it had a definite drama, public execution or corporal punishment. Who breaks a butterfly on a wheel? Who breaks a butterfly upon a wheel? - Wikipedia, the free encyclopedia

I think if you want to try someone for war crimes, there are two parts to it. One, who is the authority? If say you had poachers caught on a nobleman's land, he didn't have to send word for a judge. He hung the criminals. If a man in the city was caught drunk and disturbing the peace, he was arrested by guards under a sheriff (shire reeve) and locked up for a little stay in their prison. But who would try an international criminal? Where there is a justice system in place, there must be an authority at the helm, or you're dealing with noble justice. If the offending foreigner is noble, he may be entitled to a trial before a senate/ priest/ nobleman of higher standing. If the crimes he committed are capital offenses, he would be executed by the highest-paid executioner and it would be the monarch's approval alone that condemned him.

This is really a bigger issue than a crime and a penalty. Mary Queen of Scots was imprisoned for many years and Queen Elizabeth had a very difficult time with her execution. When someone is royal or noble, their status demands certain things like proper accommodations. If your character is foreign, he need not be treated like a dog. He may have every claim to live out his days in a plush tower, with his wife allowed to visit every weekend and stay the night. History is wonderful in all its spectacular intricacies.

I'd imagine the crimes ought to be weighed, along with the character's status. Plainly, if he's a nobody, no one will stop anyone from killing him. If he's got a name, good luck getting through the Medieval red tape. In fact, in Renaissance England, the only crimes a nobleman could be charged with were murder, treason, and felony. And anyone wearing his livery enjoyed the same invincibility. "Oh, you were drunk and punched your coachman? That's shameful, My Lord. Don't do it again in public." Ha! Okay, not really, but kinda.

So, I hope my weird law babble from history got your wheels spinning a little. Think about what you want to happen to the character, then pick the right status, social climate in the city/ country (because all were not created equal. Some cultures felt noblemen were invincible while others held the nobles to a higher standard and punished them more harshly), and a crime that gets the job you need it to do done.

Best wishes.

 

If you're literally looking for a "trial", I can suggest some interesting things from other cultures. Some natives form the Amazon would use a red-hot spoon to pour toxins on someone's hand. If the wound festered, he was found guilty and if it healed, he was set free. Of course, all it took to earn a man that scar was for someone to accuse him of stealing from them. Ouchies. I'm not sure I remember everything correctly, but in certain accusations, the accused and accuser were both wounded (burning the tongue, I think) and so if you levied a charge, you wanted to be really sure you had a case, because if your burned tongue healed slower than his, he walked and you both had a hard time eating for a week.

Witch trials were similarly interesting and unfounded in science of course, and those happened for like 300 years. Witches float, witches don't burn at the stake, etc.

Other trials may not be anything more than both parties bringing their case before the ranking noble/ senate/ prince/ governor/ etc. and the judge hearing both sides. I'm not sure what your world is like, but it seems to me if you can draw a comparison to a historical people, it might be easy to look at how they governed and conducted legal issues. Let's not forget bribery, blackmail, extortion, threats, etc. The mafia didn't invent that stuff...it's as old as the idea of fairness. If someone saw an opportunity to advance their position, they might stoop to that level, including a foreigner who is standing trial for war crimes he felt justified in committing.

And I'm just remembering a scene from Borgias, where France came through Rome and was going to sack the city, but Rome frightened France's army off with their fortification. France left, raping and pillaging and murdering their way home out of anger, and really, the only safe people were those who lived in the city. Peasants often paid the price for their warring nobles, not just invading armies. In fact some of the "code" knights lived under was regarding not killing peasants because often neighbors would have a spat and one would raid the other, cutting down field workers and commoners with abandon, and they actually had to pass a law that it wasn't kosher. Of course that was a time when human lives had less value (pre-plague Europe). Post plague, there was a lot less of that because the poorer classes became richer and suddenly there weren't enough people to work the nobles' fields. I digress. My point is that you need to weigh what a life is worth in your world. What is your character's life worth, what did his crimes cost those he offended, and most importantly, what makes the most sense for a punishment?

 

I will not try to improve on the excellent advice here regarding war crimes trials. As you can see, there really wasn't such a thing in the Middle Ages, so you're not likely to find much of use there.

So, make it up! Clearly this is going to be a set piece in your story, so construct it however you want.

You will, however, need to make the issues clear to your reader. You will want to avoid the phrase "war crime" but you can create your own. Someone did something awful, and is about to be brought to justice for it, right? Make sure your reader feels the outrage, the shock, the desire for justice. If you do that, your trial scene will be every bit as dramatic as it needs to be. It will feel real.