In Earth history, a few trial types warrant mention. We don’t mean the staid kind of today, where people calmly apply reason to presented evidence, but events like a trial by combat or ordeal. Some methods were thought to reveal the truth about the accused, even though they didn’t. Fighting was physical, of course, but imagine how those with unique powers, like wizards, might conduct these.
A specific form of proof for murders in the medieval period was cruentation, which involved making an accused murderer touch the corpse, which might start bleeding if pressed hard. This indicated guilt and seems ripe for manipulation by the wise (don’t press too hard and be exonerated!). We can leverage this to have the body react (or believed to) in different ways and for other crimes, especially with invented lifeforms, but be aware that audiences will typically scorn such beliefs as nonsense. They may feel contempt for a species or society that practices this, unless it’s true. As medical knowledge rose, specifically the understanding of how and when dead bodies naturally emit fluids; this fell out of practice because people realized it was bogus.
The goal of a duel was not to clear one’s name of a crime, but to restore honor besmirched by another. These were originally fought with swords before giving way to firearms; the former continues as the sport of fencing. In both cases, the weapons were to be similar. Established rules governed the engagement. Honor was restored in part by following these rules and by showing that honor meant enough to participants that they’d risk their life over it. Killing the other person was therefore not the goal and could actually harm the honor of the survivor. Laws against duels led to their elimination, so we should decide whether they’re still legal in our setting. Consider the values of each species and whether honor matters this much. They can duel in new ways or achieve “satisfaction” another way.
Trial by Combat
Trial by combat was essentially a duel that had been officially sanctioned, except that instead of honor being the issue, the defendant had been accused of a crime by the person whom they were to fight. This happened when no witnesses or evidence could clear up the matter. The fights took place in public and on special platforms for all to see, like a boxing ring without the ropes. Some were able to decline this combat due to handicap, age (young or old), or other factors that rendered the combat unequal. They were tried by jury instead. Priests or royalty might decline as well. If fighting a woman, men were hampered on purpose to improve equality, such as one arm tied behind the back. Another option was to choose a champion, someone to fight on behalf of the accused or accuser. We could do these if two species we’ve invented are unmatched physically.
If the defeated didn’t die in combat, he might be killed afterward, such as by hanging. In some Earth countries, depending on the crime, we could surrender when defeat was imminent, avoiding death but being dealt a harsh fate, such as slavery. World builders could extend this to include exile or, for a wizard, perhaps permanent removal of magical powers.
Trial by Ordeal
Variations on trial by ordeal exist and we can, of course, invent our own, especially if using animals or interesting places for them. Many tests were about survival, which indicated innocence, since God had saved the falsely accused. If there’s a real god of justice, maybe this trial is accurate (assuming he’s paying attention). This association with a deity led to these being carried out in church (maybe so he is paying attention!).
One version of a trial by fire was to walk several paces while holding a hot iron bar. Three days later, when the bandages were removed, an innocent person showed signs of healing while a guilty one didn’t. Walking over hot coals is a variant. We can raise the drama by using volcanoes or unnatural (magic) fire, even radiation in SF.
Ordeal by water can involve binding the hands and feet and being tossed into water; the guilty floated, the innocent sank. Either might die in the process, but a rope was tied to the accused to bring them up and prevent that. A variant involved retrieving a stone from the bottom of a boiling cauldron, the depth of which corresponded to the severity of the crime; those uninjured by this were innocent. Being submerged in cold water and surviving also indicated innocence.
We can substitute supernatural or scientific elements, such as harmful substances, radiation, or dark matter. If a species is naturally resistant to an element we’ve devised, this can be used as a test. We can use these Earth analogues as inspiration. There’s also no reason earth or air can’t be used, too. Maybe those who can survive being buried alive are innocent, or those deprived of oxygen. The latter seems obvious in space, assuming people are spacefaring and yet still this barbaric.