Eh, the history of science is littered with these. From early theories of vision involving beams cast out by our eyes [1] to phlogiston [2].
[1] https://en.m.wikipedia.org/wiki/Emission_theory_(vision)
EDIT: autocorrect
There simply isn't a formal way of determining truth. If there was it'd be in use somewhere. All the processes that work best are ones where decisions are made in a fair process where evidence is invoked, but there isn't a reasonable argument that evidence always paints an accurate picture. It simply can't. There is no process that gets all the decisions right; evidence based decision making is not enough.
If it turned out courts correctly identified the truth 80% of the time when working through cases I'd be impressed. And that is where we have formal experts doing their best with controls against bias and the potential to have independent judges making decisions. The best legal standard we have is 'beyond reasonable doubt' - I've been in plenty of situations where that standard would accept a bad conclusion; eminently reasonable people who try to make good, thoroughly considered decisions still make mistakes. Reasonable people were once extremely sexist and racist; for an easy example. For something as wide-ranging as political truth there is simply no hope.
[0] https://en.wikipedia.org/wiki/List_of_exonerated_death_row_i...
There is no way to deduce the truth using the tools in the Government's toolbox or in public discourse. The more questions systems like the courts have to answer the more mistakes they will make; they aren't for discerning the truth instead only checking that standards of evidence have been met. There are a bunch of things that are untrue but that can be demonstrated to a high standard of evidence.
When governments try to do things that are impossible there are unwelcome side effects. Since they logically can't police the truth any attempt to do so will not have the intended outcome.