Many people think that such a thing is not possible, or that the giving the Government such a power would be too much.
I personally think I could be persuaded to give such a power to the judiciary branch. I'd have to think about it a lot more before coming to a final decision, though.
Truth is a slippery concept - and i would far rather - like you- we did not have a department deciding upfront what is or is not truth.
plus this idea might have the pleasing side effect of ministerial pronouncements being testable in court - although this is politics. Johnson's "350 million a week" bus was denounced as untrue from many quarters - but it was still a winning slogan - so perhaps the problem is still not fake news, but what people want to believe and why.
However, I am honestly not sure if it's just American first amendment indoctrination that makes me think that is significantly different than deciding what is true and what isn't.
And in almost any case, the jury is tasked with determining the credibility of witnesses.
That's literally what determining facts means.
> They decide whether the evidence presented to them is sufficient to show that an event or events happened
Yes, they determine the facts—what is true and not—by weighing the evidence.
> My understanding is that even in defamation suits they are mostly trying to prove that person A said thing X about person C and then prove that person C was harmed because of it.
They also decide whether X is true, and, if so, whether Person A claimed it with knoweldge of it's falsity or reckless disregard of the truth. But the other determinations are also decisions about what is true.
In a legal sense, that's exactly what they do. Juries are, by definition, deciders of fact, i.e. they decided what is legally true based on the evidence presented to them.
Whether legal "truth," epistemological "truth," and physical "truth" coincide is an entirely separate (and largely pointless) issue.
Seriously though, libel and slander cases in the US are ridiculously hard to prove because you have to prove intent.
If you are going to address this, it seems to me to almost require a pre-emptive rather than a reactive approach.