The multiple MeatEater podcasts covering this are quite enlightening. In Wyoming, where the case being tried is, there was nothing on the books about corner crossing, but as somebody else mentioned, it was frowned upon by the game warden and sheriffs deputies just to avoid conflict. The problem is, conflict avoidance is not law.
Then you throw the big money private landowner from back east into the mix, and he becomes the greasy wheel to mess with the hunters that crossed at the fence. He said the ladder they used impeded his airspace, so he had his 'ranch-hands' put up posts on his ground and connect them with chain and 'no-trespassing' signs that crossed the corner. So the ladder was impeding his airspace, but the chain and sign wasn't impeding the public ground airspace?
Can't wait to see how the civil trial goes. The only thing he has to stand on is that allowing corner crossing reduces the value of his private property (but he won't say that the reduction is because the thousands upon thousands of acres of public ground he loses that was effectively his personal playground). I'm all for private property rights, but corner crossing should not be illegal.
In wyoming, all that checkerboard white/yellow area, all the yellow is BLM ground, each square is a square mile, and unless it has a public road going through it (not very much of it does), you can't set foot on it, even through you as a citizen 'own' it.