How might a Patent Term Adjustment affect an Obviousness-type Double Patenting analysis? | Fieldfisher
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How might a Patent Term Adjustment affect an Obviousness-type Double Patenting analysis?

Defeng Song



Cellect LLC (Cellect) owns four patents in the US, namely, ‘742, ‘369, ‘626 and ‘621, each of which is directed to devices comprising image sensors. Each patent claims priority from a single application that issued as the ‘255 patent.

Each of the challenged patents was granted a patent term adjustment ("PTA"), and all had expired even after factoring in the grants of PTA. None of the challenged patents was subject to a terminal disclaimer during prosecution which may be used to overcome a double patenting problem. The relationship of the challenged patents is indicated in the figure below:

Cellect sued Samsung Electronics, Co. (Samsung) for infringement of the challenged patents in the United States District Court for the District of Colorado. Samsung requested four ex parte reexaminations on each challenged patent, asserting that the patents were unpatentable based on obviousness-type double patenting ("ODP"). The examiner in the reexamination proceedings determined that all the challenged claims were obvious variants of Cellect’s prior-expiring reference patent claims. The asserted claims and ODP invalidating reference patents are indicated in the table, with representative claims indicated in bold.

Cellect appealed to the Board, arguing, among others, that the extended patent term granted by PTA cannot be negated by an ODP invalidating reference. The Board sustained.

Coming before the Federal Circuit Court, one major issue was which date of a challenged patent should be used for an ODP invalidating analysis; is it the expiration date with or without the extended term by PTA?

Cellect argued that where a PTA is granted, the expiration date of a challenged patent should be the date on which the patent should have expired if no PTA were granted. Cellect supports the argument by analogizing PTA with PTE (patent term extension) in that both PTA and PTE are statutorily authorized extensions of term, and should be treated the same in an ODP analysis. Since PTE cannot be cut off by ODP as per the court’s precedents, PTA cannot be cut off either.

The court rules against Cellect, considering the different statutory languages in '154 on PTA and 156 on PTE. In particular, '154 has a disclaimer limitation on PTA allowing terminal disclaimer to cut off a PTA, while there is no such limitation on '156. The court also found support in the court’s precedents like Abbvie, where the court held ODP continued to apply where two patents claiming the same invention had different expiration dates, including where the different expiration date was due to a grant of PTA. 

Therefore, the court concluded that an ODP analysis on the patent that has received PTA must be based on the expiration date of the patent after PTA has been added. The full text of the decision can be found here.


The Cellect case may give a heads-up that when an applicant builds a patent portfolio centering around one invention in the United States, special care should be taken to avoid timewise extension of patent term on the same or patentably indistinct inventions through continuation, continuation in part or divisional application. Further, when a PTA is granted to a member of the patent family, the extended term via PTA could be a double-edged sword in the sense that while it prolongs the patent protection, it also increases the chances of the patent being invalidated in a double patenting analysis. 

The reason why double patenting comes up under US law is that an inventor’s earlier US patent/applications are excluded from the scope of prior art against the same inventor’s later US patent/applications under 35 USC 102 (a) (2) or pre-AIA USC 102 (e). This will give rise to a situation where the same inventor may own multiple patent/applications on the same invention at the same time. US patent law uses terminal disclaimer and ODP analysis to overcome the double patenting problem, whether statutory double patenting or judicially created non-statutory double patenting. 

To contrast, no terminal disclaimer mechanism is available under Chinese law. In China, any earlier patent/application can be used as prior art against a later patent/application, whether they are owned by the same applicant or not. So, double patenting issue can be largely curbed at the prosecution stage. Even if such prior art is not noticed at the prosecution stage, it could be still be used in invalidating the patent after the patent issues. That said, double patenting may still come up under Chinese law under limited circumstances where there is a coexistence of multiple patent/applications that are directed on the same invention and have the same effective filing date, either owned by the same applicant or by different applicants.

If the competing patent/applications are owned by the same applicant, the examiner will request the applicant to drop one or amend one so as to avoid double patenting; if they are owned by different applicants, the examiner will request the applicants to negotiate, and if no result comes out of the negotiation, all the competing patent/applications would be rejected.

But, double patenting under Chinese law only refers to patent/application claims that have the same protection scope, which is largely a novelty test. For non-obviousness type of double patenting as illustrated in the Cellect case in the US, there is no explicit rules addressing this issue under Chinese law for the moment.

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Intellectual Property