Presumption of validity attaches to all issued patents, even incorrectly issued patents

| July 5, 2012

Sciele Pharma Inc. v. Lupin Ltd.

July 2, 2012

Panel: Lourie, Prost, Moore.  Opinion by Moore


Shionogi (new name for Sciele Pharma) obtained US Patent No. 6,866,866 (“the ‘866 patent”) which included broader claims that were intended to be cancelled in favor of narrower claims in response to a rejection.  Shionogi brought suit against Lupin for infringement of the ‘866 patent including claims that were to be cancelled.  Lupin began selling the alleged infringing product and Shionogi moved for a preliminary injunction.  The District Court granted Shionogi’s request for preliminary injunction and Lupin appealed.  On appeal, the CAFC stated that even though the ‘866 patent issued with the incorrect claims, the ‘866 patent nonetheless had a presumption of validity and that the clear and convincing evidentiary standard applied for invalidating the patent.  The CAFC also stated that there is not a heightened standard just because references were considered by the PTO.  With the proper clear and convincing evidentiary standard applied to the ‘866 patent, the CAFC stated that Lupin has raised a substantial question of invalidity, and thus, the preliminary injunction is vacated.


The ‘866 patent is to “Controlled Release Metformin Compositions.”  Claim 1 recites “a mean time to maximum plasma concentration (Tmax) of the drug which occurs at 5.5 to 7.5 hours after oral administration on a once-a-day basis to human patients.”  Some dependent claims narrow the Tmax range to 5.5 to 7.0 hours.

During prosecution of the ‘866 patent, the Examiner rejected the claims as being obvious.  In response, Shionogi cancelled a number of claims including claim 1, and rewrote claim 5 (having a narrower range for Tmax of 7.0 hours) into independent form.  The Examiner agreed in an interview that claim 5 having an upper Tmax of 7.0 hours is patentably distinct over the cited references.

Despite the amendment, the Examiner issued a Notice of Allowance in which the claims including cancelled claim 1 were allowed.  Applicants informed the PTO of the mistake, and the Examiner issued a supplemental Notice of Allowance acknowledging the amendment in which claims having the upper Tmax of 7.5 hours were cancelled and the claims having the upper Tmax of 7.0 hours were allowed.  However, the ‘866 patent issued with the cancelled claims having the original upper Tmax of 7.5 hours.

The ‘866 patent was listed in the Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book) entry for a drug called Fortamet.  Lupin filed an Abbreviated New Drug Application (ANDA) seeking approval to market a generic version of Fortamet certifying that the ‘866 patent was invalid, unenforceable and/or not infringed.  Lupin attempted to launch its generic Fortamet.  Shionogi filed suit for patent infringement and moved for preliminary injunction.

The District Court granted the preliminary injunction concluding (1) that because prior art references were previously before the PTO, there was an added burden of overcoming the deference that is due to a qualified government agency presumed to have done its job; and (2) that KSR was not directly applicable because the prior art was before the PTO when the ‘866 patent issued.  Lupin appealed the grant of the preliminary injunction, and the CAFC vacated the preliminary injunction.

Factors for assessing a Preliminary Injunction:

(1)  a reasonable likelihood of success on the merits;

(2)  irreparable harm if an injunction is not granted;

(3)  a balance of hardships tipping in its favor; and

(4)  the injunction’s favorable impact on the public interest.

“To demonstrate a likelihood of success on the merits, a patentee must show that, in light of the presumptions and burdens that will inhere at trial on the merits:  (1)  the patentee will likely prove that the accused infringer infringes the asserted patent; and (2) the patentee’s infringement claim will likely withstand the accused infringer’s challenges to the validity and enforceability of the patent.”

I.  Presumption of Validity

Lupin argued that the presumption of validity should not apply because of the erroneous issuance of the cancelled claims.  Shionogi argued that there should be a heightened presumption of validity because the prior art references relied upon by Lupin were before the PTO during prosecution.

CAFC stated that “the presumption of validity attaches to all issued patents and the clear and convincing evidence burden applies to all issued patents.”  Whether a reference was previously considered by the PTO, the burden of proof is the same:  clear and convincing evidence of invalidity.  There is no heightened or added burden that applies to invalidity defenses that are based upon references that were before the PTO.  Whether a reference was before the PTO goes to the weight of the evidence.  New evidence may carry more weight than evidence previously considered by the PTO.

CAFC also stated that the fact that the claims of the ‘866 improperly issued does not change the presumption of validity.  However, the unusual circumstances of the issued patent including the incorrectly issued claims can be taken into account when considering the prosecution history of the ‘866 patent for determining validity.

II.  Obviousness Analysis

The district court failed to properly apply KSR focusing on the fact that references cited by Lupin (Cheng and Timmins) were before the PTO during prosecution.

The Cheng reference discloses all of the limitations of the asserted claims except for the Tmax range of 5.5 to 7.5 hours.  Cheng discloses a Tmax of 8 to 12 hours.  The Timmins reference discloses a Tmax within the range recited in the asserted claims.  CAFC cited several benefits disclosed in Timmins due to the lower Tmax for providing motivation to combine the references.

In addition, while arguing for enablement, applicants asserted “that one skilled in the art would be able to manipulate the processes and formulations of the prior art by other methods to obtain the claimed pharmacokinetic parameters of the present invention by routine experimentation.”  Shionogi argued that this statement applies only to the issue of enablement.  CAFC stated that the applicant’s characterization of predictability and skill in the art during prosecution provides further evidence that it would have been a routine and obvious design choice to make an extended release dosage form with a lower Tmax.


In litigation, argue the weight that should be given to references depending on whether they have been considered by the PTO and not that there is a heightened or lowered evidentiary standard.  New evidence may carry more weight for satisfying the clear and convincing standard.

During prosecution, be careful of the statements you make when arguing enablement.  Any statements used to argue enablement may be used against you to invalidate claims for obviousness.

Full Opinion

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