I am currently watching the Depp/Heard trial, and there seems to be a lot of stuff that cannot be shown, or said, and a lot of people i would expect to make a statement are absent. My guess is that there are rulings in place that preclude certain witnesses from being called, certain evidence from being shown, and certain topics from being broached - but how, and why? And are those constraints known to the jury? For instance, there was a last minute witness that somehow offered herself up to testify, a very crucial character witness, that i would have thought the plaintiff would spare no expense in finding. There was a photo expert that was somehow prevented from talking about colors, there is a lot of confusion about the existence or non-existence of a wall mounted phone, but both parties have refrained from showing images of the wall that the phone should have hung on - although the existence of such photos is a near certainty, etc.
So my questions: How are such no-show-no-tell boundaries established, does the jury get to know them, and is this also in the public record somehow?