So, given current US patent law, if SpaceX has some system/method/etc that is patentable material, but that they've chosen to retain as a trade secret, and someone else comes along and rediscovers the thing and patents it, then absolutely, SpaceX may then be in violation of that patent.
That's because, as of 2011, the US (and basically the rest of the world) works on a first-to-file basis:
Meaning: "In a first-to-file system, the right to the grant of a patent for a given invention lies with the first person to file a patent application for protection of that invention, regardless of the date of actual invention."
Obviously this is not without controversy! The upside is it drastically simplifies patent filing, litigation, etc, since there can be no debate about who was the first to file a patent for an invention. But, as you point out, there are significant downsides.
I would claim FITF ultimately encourages patenting and thus public disclosure of inventions, which is overall better for the world than one dominated by protections with trade secrets. But I can't claim to have put a lot of thought into that position...
Do you think that documenting the tech and publishing a hash of the document would help? I've seen some services that offer to do this, but I'm not sure if this would work in a court of law.
First off, some background. In order to prevent someone else from patenting your idea, absent being the first to file it yourself, you need to disclose it in such a way that it qualifies as "prior art", thereby rendering invalid any subsequent attempts to patent the invention.
Now, what does that disclosure look like? First, let's talk about the Enablement Requirement:
Quoting from that section: "The information contained in the disclosure of an application must be sufficient to inform those skilled in the relevant art how to both make and use the claimed invention."
This is a general requirement both for patents, and for relevant prior art. In particular, with respect to prior art specifically, if you look at 2121 part III of the Manual of Patent Examining Procedure (https://www.uspto.gov/web/offices/pac/mpep/s2121.html
) you find the term "enabling disclosure":
"A prior art reference provides an enabling disclosure and thus anticipates a claimed invention if the reference describes the claimed invention in sufficient detail to enable a person of ordinary skill in the art to carry out the claimed invention"
There's also some rules about a POSITA being able to find the prior art. For example, with respect specifically to publications, in section 2128.2 of the manual (https://www.uspto.gov/web/offices/pac/mpep/s2128.html) we find:
"'A reference is proven to be a "printed publication" "upon a satisfactory showing that such document has been disseminated or otherwise made available to the extent that persons interested and ordinarily skilled in the subject matter or art, exercising reasonable diligence, can locate it."'
So just writing down the invention and sticking it a drawer doesn't count! The inventor must have been able to find the prior art.
Anyway, this is all to say: Simply publishing a hash of a document to prove you have it is almost certainly not sufficient to invalidate a patent application, since such a disclosure clearly doesn't meet the Enablement Requirement for prior art, nor does it meet the requirement for being discoverable.
As a random aside: this touches on why the idea of defensive patenting or defensive publication exists. Suppose you come up with an invention where protection of the invention (either patent protection or trade secret) has no value to you, but where you want to avoid being sued by someone else in the case of independent invention.
In that case, it's not at all uncommon to file a patent application or otherwise disclose the invention in a notable publication (like, say, a journal) so as to prevent someone else from acquiring a patent on that invention. And note I say "application". You don't need to be granted the patent! The application is enough to qualify as prior art (and in fact it's not at all uncommon to see abandoned patent applications cited as prior art by patent examiners in patent prosecution wrappers, which are publicly available to anyone via the USPTO Public Pair system).
