Well, to put it precisely, an omniscient being would theoretically be capable of knowing today's state of the law with probabilities assigned to the results.

I'm serious. Pick any non-trivial issues of law, ask a world leading expert, and you'd very quickly hear the word "probably" somewhere. Less often than "it depends", but you'll hear those words often nonetheless.

If that's "knowable" to you, I guess it's knowable.

Someone has to be in the news first, and then you learn about it. To that someone, the change you see in tomorrow's legal news is today, was yesterday. It's more a gamble than you think, you just don't feel it until it bites you.