Context: This is a world inhabited by intelligent, non-anthro animals, some of which have decided to outlaw hunting and eating prey in favour of living in harmony and cooperating.
They have a zero tolerance policy for predation and it is criminalized extremely heavily. Depending on what species or taxon you are (all animals have the right to be tried by members of their own species and taxa, and they are responsible for carrying out sentences of their own kind too), First Degree Predation, where you personally kill then eat an animal, is the only crime that formally carries the death penalty. Regular first degree murder where you "merely" kill an animal without intent to eat them only has a maximum sentence of life in prison without parole. Second Degree Predation (aka Simple Predation) is where you obtain meat with the intention of eating it without personally killing anything, carries only a mandatory fixed term prison sentence in addition to losing certain freedoms post release.
However, their laws on the issue is very much based on intent as that is their philosophy, that because they are all sapient and no longer bound by their natural hunter instincts, they are responsible for their own actions. You don't have to actually eat the prey you killed to have committed First Degree Predation, and the inverse is technically true as well, where if you kill an animal for some other reason and only after they're dead do you decide to eat them, then you're technically only guilty of murder and Second Degree Predation instead of First Degree Predation. There are also legal ways that certain animals can obtain animal tissue, for example, as skin grafts and organ transplants, autopsy and forensic investigations, or for general research. Because animals handling tissue in these cases don't intend to eat it, it does not fall under Second Degree Predation. However, if you buy animal meat and later decide not to eat it, that's still considered predation.
Especially with the nature of eating and digesting food, law enforcement only has a very small time window to order a suspect to undergo lab testing of what's in their belly where it will actually show a positive hit for animal tissue, so my original thought is that the intent clause is meant to make prosecuting predation easier, since they wouldn't need to actually prove that the accused has animal tissue in their digestive tract at any point, just that they wanted at some point for some form of animal tissue to end up inside them.
I know there are many real life laws that use intent in a similar way, but I don't know how courts actually prove intent beyond a reasonable doubt. Can anyone who's delved more into the legal side of worldbuilding comment on how the courts in my world might prove (or disprove) that someone intended to eat another animal when they do not have direct evidence that the animal was indeed eaten?
Dang! There's some brilliant ideas in there! I can see a lot of possible stories in that world, just from this one section of history. Groups rebelling, serial predators, the legal aspect you were asking about, etc. I'll come back to that in a sec, I promise.
But it makes me curious about how "they" handled the divide between social/group species and those that are either loners or only live in small family groups. When you have the time, anyway :)
But, on the legal side of things, my series that I'm writing is around forensics in a magical world, so I've done a little bit of looking into mens rea. What you're asking is essentially that, how to prove the accused was committing the crime intentionally.
With animals, you aren't able to use something as concrete as having purchases and practices with a new weapon, or looking up how to kill in a given way (or likely wouldn't very often). If they're hunting, they have weapons already. There's also the difficulty with crafting weapons that will work for more than one type of animal, but that's tangential.
I think where your critters are going to find mens rea is in the animal part of the accused. Most predators exhibit predictable behaviors before hunting. Most don't hunt for anything but food, so if they exhibited hunting behaviors, that's good indication that they had intent to hunt, rather than it being a killing for other reasons.
But! There are species that will engage in hunting behaviors without intending to kill, and might not eat the prey even if they do kill. That's not unusual for cats that are otherwise well fed. You'll see it in other domesticated predators as well (though not as often as cats). But it happens with captive animals sometimes.
So the animal courts in your world have it a lot harder proving intent to eat. Well, unless a faction of hardliners pushed through a law making the evidence of eating evidence of intent to eat. That's really the only way I can think of to make it any less difficult than it is for humans in our world. Proving intent is usually about stringing together "circumstantial" evidence (which isn't the weak thing people often think it is. Motive, intent, and opportunity are often built on nothing but circumstantial evidence).
So I think you'd run into a lot of variations of case law where mens rea is proven in different ways for the various genera, and possibly even on a species specific level. You'd have canids that would have intent hard to prove because they have very little prior intent behaviors. They tend to take hunts more loosely at the beginning unless, and use persistence tactics (depends on the species a lot, though) prey drive is triggered suddenly. Cats, though, run high to stalking behaviors, so evidence of them stalking is going to be fairly convincing that they were hunting for food rather than having killed someone over a disagreement.
Something like a bear doesn't usually kill at all unless it's going to eat, or it's being threatened, so the fact of eating is an even stronger indicator of intent, and if there's exacerbating evidence as well, conniving a jury gets easier.
As a loose example, say that a cat was found to have killed a mouse. If there's video footage of it crouched down, with its tail twitching and legs moving to keep them prepped for a pounce, that's almost incontrovertible proof they were killing prey. But if the mouse had run out in front of them and they just swiped with claws and then bit, it would point towards an impulse kill, instinct overwhelming the conscious mind.
If the pouncing cat had also been seen following a scent, well, kitty is in trouble because even other cats would recognize that. But, maybe if the cat had been hunting after a blow to the head, the jury might decide that it couldn't form legal intent, and thus only be liable for the killing itself, not the eating.
There's a metric buttload of case law on mens rea, and reams of writing used in law schools on how to prove it. Waaay more than I've ever waded through tbh. But I think that's where your direct research would need to go. Most counties have law libraries that the public can access (I think, I know mine does, and it's a fairly poor county). Not sure what access would be like outside the US, but there's usually online access to at least the actual legislation around such things, and a lot of sites exist for legal info.
Dunno if that helps or not.
A lot of interesting info for me to think about, thank you!