Let's start with the (pre-AIA) statute. 35 U.S.C. 102(e) says that one type of prior art may be where:
the invention was described in ... a patent granted on an application for patent by another filed in the United States before the invention by the applicant for patent...This is a pretty old rule, dating back to the Alexander Milburn case. The gist of the rule is that delays in the patent office should not deprive references of being prior art. Thus, even though the patent application is "secret" until published, we backdate the reference to the date of filing once the patent is granted (or the application published, which is covered in a subsection I do not reproduce above).
The issue in Ariosa v. Illumina is what to do with provisional patent applications. For the reference at issue, the prior art patent first relied on a provisional patent application, which is never published but becomes publicly available if a patent that relies on it is granted. Later, a regular patent application was filed and eventually issued. There is a dispute about whether the invention was even described in the provisional, but we'll assume that it was. However, the PTAB ruled (and the Fed. Cir. affirmed) that because the issued patent claims were not supported by the provisional patent disclosure, then the reference could not be backdated to the filing of the provisional patent, even if the invention was described in the final patent.
This is where the objections come in. If the patent relies on the filing date of the provisional patent (and incorporates it by reference), then surely it is described as of the provisional patent date and should be prior art. We are, after all, living in a first to invent world and it is unfair that the first inventor (in the provisional patent) should not count as prior art.
Let's start with Alexander Milburn. I love that case. I have assigned it to my students. I think it explains this statute well. But it is not controlling. It was an interpretation of the statute at that time. We have a later adopted statute that defines what is and is not prior art, and Alexander Milburn does not speak to the facts of the Ariosa dispute because there were no provisional patents at that time. This is not like, say, on sale (Section 102(b)) in Helsinn in which that statute remained unchanged and the meaning of the words remained unchanged. There were no provisional patents when Alexander Milburn was granted, and thus it has little to say; the statute was intended to deal with that (and even that has a difficult time).
As a corollary to this analysis, I want to put the rest that there is a problem with the Federal Circuit's rule because it rewards the second inventor. I would bet dollars to donuts that many people arguing this scoffed at complaints that the AIA's first to file rule was unconstitutional because it rewarded second inventors. Both arguments fail for the same reason - the patent system has a long history of allowing the second invention to issue as a patent under certain circumstances. Indeed, even the current version of 102(e) disallows many early foreign patent filings, even though such filings are clearly the first invention. Once again, we have to look at the statute.
So, let's look at the statute: "The invention is described in" - critics focus on this, saying it makes no sense to look at a patent's claims. We only care about whether the invention was described. Fair enough - I agree.
But what about the next part: "a patent granted on an application for patent by another filed in the United States before the invention." Looking at this in pieces, we see a few requirements. First, the description must be in the patent, not the provisional application. Thus, looking at what the provisional patent says should be irrelevant...for this piece.
Second, that description must be in a patent "granted on an application for patent...filed...before." This is where the action is. What does it mean for a patent to be granted on an application for patent filed? For a provisional application, means that the patent must satisfy Section 119(e). It must be filed within one year, and the final patent claim must be supported by the written description of the provisional patent. It is as simple as that - the plain words of the statute dictate the Federal Circuit's rule.
There is a policy benefit to this reading. I think that patentee's can take advantage of the jump from provisional to final patent disclosures, adding new matter while always claiming priority back to the provisional. The provisional patent is not easily obtained, and it takes work to parse out which claims are actually entitled to the earlier filing date. Enforcing the rules on prior art better incentivizes complete provisional patent disclosures.
Then why do I say this is an uneasy case? Well, did I mention that I like Alexander Milburn? The policy it states, that delay in the patent office shouldn't affect prior art can easily be applied here. So long as the description is in the provisional patent, and so long as that provisional patent is eventually publicly accessible, then the goal, even if not the strict language, of the statute is met.
Also, my reading leads to a potentially unhappy result. A party could file a provisional that supports invention A, and then a year later file a patent that claims invention A but describes invention B. The patent could then be asserted against B while relying on the earlier filing date of A, even though B was never described in the provisional as of the earlier date. Similarly, a provisional patent could describe B, and B could then be removed from the final patent application, and the patent would not be prior art because B was not described in the patent, even though B had been described in the earlier, now publicly accessible provisional application.
I don't know where I land on this - as readers of this blog know, I tend to be a textualist. Sometimes the Court has agreed with that, but sometimes (see patentable subject matter and patent venue) it does not.