New Patent Law

[Aaron]

inventorship

Looks fairly clear to me, if your not an inventor, you cannot file legally.
Therefore if a patent was granted to a non inventor of an invention the
patent would be invalid.

Yes, but we have to account for the fact that people lie.

Someone can see an invention, make up a bunch of notes, etc... and present them as proof of inventorship but that much probably isn't needed.

The patent process doesn't seem to require much proof at all - there is simply an oath an inventor takes to swear they're the inventor.

When one crook claimed my invention was his innovation, he took an oath - the "proof" was this crook's circuit that he actually copied from my schematic!

I don't think it can be assumed people are going to be automatically honest in their inventorship claims. If so, then the "first inventor to file" doesn't mean a whole lot as anyone could stage themselves to be an inventor.