US CAFC finds obviousness-type double-patenting based on PTA (In re Cellect LLC)

The US Court of Appeal of the Federal Circuit (CAFC) recently considered the interaction between two peculiarities of the US patent system, patent term adjustment (PTA) and obviousness-type double patenting (ODP) (In re Cellect LLC). This is the first time that CAFC have considered the implications of PTA for ODP. The decision has implications for the value of PTA to patentees by establishing the risk that PTA may invalidate a patent post-grant for obviousness-type double patenting. 

More patent term: Patent Term Adjustment and Patent Term Extension

The general rule across jurisdictions is that patents expire 20 years from the original filing date of the patent application. One exception to this rule is the patent term adjustment (PTA) provisions in the US (35 U.S.C. § 154). In the US, PTA may be added to a granted patent to compensate the patentee for delays in patent prosecution. PTA can provide anything from an additional day to years of extra patent term. 

PTA is not to be confused with patent term extension (PTE), whereby a US patent for a pharmaceutical drug product may be extended by a maximum of 5 years following FDA approval for the drug product (35 U.S.C. § 156) (broadly equivalent to supplementary protection certificates (SPCs) in Europe).  

Obviousness-type double patenting and terminal disclaimers

In the US, obviousness-type double patenting prevents a patentee from securing a patent for subject-matter that is not novel and non-obvious over an earlier expiring patent owned by the same patentee. According to established case law, obviousness-type double patenting may apply to patents having different expiry dates due to PTA. PTA may, for example, be granted for a continuation or divisional patent, but not for the original parent patent. The parent patent would then have a patent term of 20 years from the effective filing date, whilst the term of the original patent may extend days, months or even years beyond this. If the subject matter of the later patent is obvious in view of the early expiring patent, the later patent application may be rejected for obviousness-type double patenting. 

An objection of obviousness-type double patenting may be overcome by filing a terminal disclaimer (35 U.S.C. § 253).  A terminal disclaimer limits the term of a patent to that of the earlier patent, so that both patents have the same expiry date. The patentee particularly disclaimers any patent term beyond the expiry date of the earlier expiring patent.

Double-trouble

The double-patenting provisions in Europe are, in contrast to the US, fairly lenient. In Europe, the same patentee may not be awarded two patents with the same filing date for the same subject matter, where "the same subject" is currently interpreted relatively narrowly (G 1/05 and G 1/06). However, the EPC also has nothing equivalent to US patent term adjustment or terminal disclaimers.

Case Background: In re Cellect LLC

In this case, Cellect sued Samsung for infringement of four patents in the same family (US 6982742, US 6424369, US 6452626 and US 7002621) relating to image sensors for phones.  In response, Samsung brought invalidity proceedings against the patents on the grounds that they were invalid for obviousness-type double patenting. 

All four of the Cellect patents claimed priority from the same provisional application (US 09/496,312). Without patent term adjustment (PTA) all four patents would therefore have expired on the same day, 20 years from the effective filing date (6 Oct 1997). Instead, each of the four patents had been granted with various amounts of PTA (pre-AIA 35 U.S.C. § 154(b))

Samsung submitted that the 4 patents were invalid for obviousness-type double patenting over another patent in the same family. The earlier patent had not been granted PTA and therefore had an earlier expiry date than all 4 of the patents in contention (US 6862036). Crucially, obviousness-type double patenting had not been raised by the Examiner during prosecution of the four later patents and no terminal disclaimers had been filed. The patents therefore all had different expiry dates. 

The key questions for the Court of Appeal of the Federal Circuit (CAFC) was whether obviousness -type double patenting should be assessed based on the expiry date of a patent before or after PTA is taken into account, and whether a terminal disclaimer could be retroactively filed to overcome the ODP objection. 

Adjustment or extension?

Celletis argued that obviousness-type double patenting should be assessed based on the expiry date of the patent before PTA. Cellectis cited case law relating to obviousness-type patenting and patent term extension (PTE) (not PTA). Particularly, under Novartis v. Ezra Ventures (Fed. Cir. 2018), obviousness-type double patenting does not invalidate a patent that has a later expiry date due to PTE (35 U.S.C. § 156). Cellectis argued that the same principle should apply to PTA. 

The CAFC did not agree with Cellectis's arguments. The CAFC instead found that "PTA and PTE are dealt with in different statutes and deal with differing circumstances". For the CAFC, the correct expiration date for obviousness-type double patenting analysis is the date after PTA. By contrast, the CAFC confirmed the existing case law with respect to obviousness-type double patenting, terminal disclaimers and PTE:

"ODP for a patent that has received PTE should be applied based on the expiration date (adjusted to a disclaimed date if a terminal disclaimer has been filed) before the PTE is added, so long as the extended patent is otherwise valid without the extension."

As mentioned above, during prosecution an objection of obviousness-type double patenting may be overcome by filing a terminal disclaimer. Unfortunately for Cellect, it is not possible to file a terminal disclaimer for patents that have already expired. All 4 of the contentious patents had expired, even taking into account the PTA. It was therefore no longer possible for Cellectis to rescue the patents by filing terminal disclaimers. As the CAFC noted, a terminal disclaimer “is not an escape hatch to be deployed after a patent expires.” 

The CAFC concluded by reaffirming the decision of the USPTO and Patent Trial and Appeal Board (PTAB) that the patents were invalid for obviousness-type double patenting. 

Final thoughts

The CAFC noted in their decision during prosecution of the patent "the examiners had the opportunity, and perhaps the obligation, to reject" the claims for obviousness-type double patenting, but did not do so. Had the Examiner's raised an ODP rejecti, it is likely that the patentee would have filed terminal disclaimers and the subsequent invalidation for ODP would then have been avoided. 

The burden placed on the patentee to disclaim patent term placed on the patentee by this CAFC decision is reminiscent of the burden on patentees in Europe to avoid the added-matter trap (i.e. whereby matter added to the claims, even by an Examiner, may irreparably invalidate a patent post-grant). However, unlike the added matter trap, terminal disclaimer may at least be filed post-grant, the cut-off point being the expiry date of the patent. The decision in CAFC therefore does not create a completely doomsday scenario with respect to PTA. Nonetheless, the CAFC decision is certainly food for thought. In light of Cellectis, patentees must now weight the risk of invalidation due to ODP against the benefits of a long patent term provided by PTA.

Further reading

Double trouble: EBA finds legal justification for the prohibition of double patenting (G4/19) (July 2021)