In invalidity proceedings, entitlement to priority may mean the difference between anticipating prior art and a useless reference.

In Patent Trial and Appeal Board proceedings, a fast pace and limited ability to supplement the record mean both petitioners and patent owners must come prepared with evidence and arguments supporting a given priority date for challenged claims.

For pre-America Invents Act claims, a patent owner can swear behind some references by showing earlier conception and diligent reduction to practice, as long as corroborated evidence shows the inventor was in possession of their invention.

But the possession requirement also prevents a patent owner from obtaining claims that lack written description support. With the passage of the AIA, an earlier date of conception no longer helps a patentee overcome prior art.

However, the possession requirement remains as a way to prevent claiming more than the inventor possessed as of the filing date. This applies even in an IPR, where the PTAB will not invalidate claims merely for lacking written description, but will consider entitlement to priority in the context of determining what prior art might apply against the challenged claims.

PTAB practitioners should be mindful of the evidence the PTAB considers for conception, diligence in reduction to practice, and possession, to build complete positions.

Bolstering the Factual Record

Take, for example, the Nov. 21, 2022, Unified Patents LLC v. Gesture Technology Partners LLC decision.[1] Unified Patents challenged Gesture’s handheld computer apparatus claims based on a reference that was filed a mere nine days before the critical date of the challenged claims.[2] Gesture swore behind the asserted reference by submitting a declaration from the Canadian named inventor of the challenged claims.

The declaration explained that the date written on the challenged claims’ provisional application — two days before the filing date of the cited reference — was the date that the provisional application was drafted.

So, according to the declaration, the invention was conceived no later than that date. The declaration also explained that the 10-day delay between drafting and filing was due to holidays in Canada and the U.S.

The PTAB credited the conception date testimony as unchallenged. And the PTAB found the 10-day delay reasonable in view of the holidays, so the inventor and attorney were diligent in constructively reducing the invention to practice by filing a provisional patent application.

The PTAB also determined that the challenged claims were supported by the provisional application. Not only were the provisional and nonprovisional applications nearly identical, but Gesture submitted a listing of support by claim element.

Obvious With One’s Own Petard

Also take the Dec 9, 2022, Netskope Inc. v. Bitglass Inc. decision.[3] Netskope challenged Bitglass’s secure data transfer patent based on the challenged patent’s own parent application, Kahol.

Kahol shared an identical specification with the challenged patent but published over one year before the application maturing into the challenged patent was filed. So Netskope’s challenge turned on whether the written description supported the challenged claims — i.e., whether the written description showed that the inventor possessed the challenged claims as of the parent’s filing date.

As the PTAB found, Kahol’s figures depicted two separate embodiments for use of a proxy in secure data transfer over a network.

First, Kahol showed a central directory that accepts a login and directs a user to an application server through a proxy. Then, in a separate figure, Kahol showed two separate proxies:

  • A Security Assertion Markup Language, or SAML, proxy for login; and
  • An application proxy to direct the user to an application server.

The challenged claim, however, claimed both actions taken by a central directory and an application proxy, but no SAML proxy.

The PTAB found that Kahol’s specification did not explain how to create a secure data transfer system that uses an application proxy but no SAML proxy. So the specification did not demonstrate that the inventors were in possession of the claimed invention, and the challenged claims lacked written description support.[4]

And, as the PTAB found, the fact that a skilled artisan would have known to use a central directory to perform the functionality of an SAML proxy, as claimed, is of no moment if the specification treats the central directory as separate from the SAML proxy.[5]

In contrast, the enablement requirement, which the PTAB did not consider, would have accounted for the knowledge of a skilled artisan in determining whether the specification teaches a skilled artisan to make and use the claimed invention.[6]

Because the challenged claims were not entitled to the priority date of the parent application, the Board found that the challenged claims’ own parent, along with another prior art reference, rendered them obvious.

Caught in the Squeeze

Finally, take the Nov. 15, 2022, Pfizer Inc. v. uniQure Biopharma B.V. decision.[7] Pfizer challenged uniQure’s patent directed to administering a nucleotide sequence for a modified Factor IX polypeptide as gene therapy for hemophilia B — which is caused by a deficiency in Factor IX.

Pfizer challenged uniQure’s patent based on a reference published between the filing date of a parent application and that of the application that matured into the challenged patent. So, just as in Netskope, the PTAB had to determine whether the challenged claims were supported by the challenged patent’s written description and therefore entitled to claim priority to the parent application.[8]

The PTAB split its analysis into two sets of claims. The PTAB found the first lacked written description because the specification did not recite certain claimed expression levels.

For these claims the PTAB found that, at most, the specification demonstrated that a skilled artisan would have wanted to achieve a lower expression level with a modified Factor IX polypeptide than wild-type Factor IX. The PTAB found that this potentially spoke to obviousness but not written description.[9]

Without demonstrating that the inventor possessed the claimed invention as of the parent’s priority date, uniQure could not show that its claims were entitled to that date.

Similarly, the PTAB found the second set of claims lacked written description because they claimed administering a dose of adeno-associated virus, or AAV, vector. But the specification never recited doses of AAV, only doses of adenovirus. And, to support nonobviousness in another ground, uniQure’s own expert testified that the appropriate dose of adenovirus does not inform the appropriate does of an AAV vector.

Then, the PTAB found that uniQure did not dispute that its challenged claims were unpatentable if they were not entitled to their priority claim. So the PTAB found uniQure’s claims anticipated and obvious.

The Endgame: Explaining Obviousness Through Written Description

By taking lessons from Gesture Tech, Netskope and Pfizer, PTAB practitioners can build an early record of evidence demonstrating why challenged claims are entitled to a given priority date — or not.

Where applicable, practitioners can prepare early evidence showing diligence — or lack thereof — between a critical date and reduction to practice.

And where necessary practitioners can demonstrate the presence or absence of features in an earlier-filed written description.

By acting early, PTAB practitioners can work creatively to build the strongest possible obviousness or nonobviousness position, even if it is tied to a written description challenge to priority.

Originally printed in Law360 on January 30, 2023.