Certificate of correction invalid, infringement case continues with original claimsApril 4, 2007

The Federal Circuit yesterday voided a certificate of correction which had been issued changing the scope of a patent's claims. Because the error corrected broadened the claims and was not the type of error that was "immediately apparent and leave no doubt as to what the mistake is," the certificate of correction was inappropriate. As a result, the finding of infringement under the "corrected" claims was vacated, and the case remanded for a determination of infringement of the original, uncorrected claims.

The court also addressed some procedural issues. The court found the alleged infringer had waived its right to argue an additional claim term should have been construed by failing to raise it at the lower court during the claim construction phase of the case. The infringer also alleged inequitable conduct in its answer based in part on a failure to disclose material prior art references to the USPTO, but did not allege what relevant prior art was known and not disclosed. As a result, the inequitable conduct pleading did not meet the requirements of Rule 9, and was dismissed. Three years later, the infringer asked for leave to amend its allegation to provide the necessary details, but this request was denied as untimely. The Federal Circuit found no abuse of discretion in this decision.

More details of the case after the jump.

Central Admixture Pharmacy Services is the exclusive licensee of the '515 patent relating to chemicals used during heart surgery to prevent heart tissue death when the heart is without a continuous supply of blood. Advanced Cardiac Solutions sold a competing product, and as a result CAPS, along with the inventor, sued for infringement. Claim 1 is representative, and requires:

1. In an amino acid enriched cardioplegic solution for use in treating human hearts to prevent or reverse heart muscle damage due to ischemia, said cardioplegic solution having a calcium ion concentration, a metabolizable substrate concentration and an osmolarity, wherein the improvement comprises: maintaining said calcium ion concentration of said cardioplegic solution at a lowered level of between about 50-300 μmol;

maintaining said concentration of metabolizable substrate in said cardioplegic solution between about 400-1000 mg % wherein said metabolizable substrate is selected from the group consisting of glucose, fructose, a salt of malic acid, a salt of succinic acid and a salt of pyruvic acid; and

maintaining said osmolarity of said cardioplegic solution at an increased level of between about 400-500 mOsmol.

(emphasis added). The patent issued on January 29, 1991. On December 15, 1999, CAPS applied for a certificate of correction under 35 U.S.C. § 255. CAPS sought to replace all instances of "osmolarity" in the patent with "osmolality," including those in the claims such as claim 1 above (mOsmol). The two units of measure are similar, but not identical: osmolarity is osmoles/liter whereas osmolality is osmoles/kilogram. The USPTO issued the certificate of correction on January 30, 2001, after the complaint in this case was filed, and the net result of the correction is to reduce the concentration required by the claims by approximately 1-2%.

During the case, ACS challenged the validity of the certificate of correction. In order to be valid, a certificate of correction must "not involve such changes in the patent as would constitute new matter or would require re-examination." When a certificate of correction broadens a claim, it is valid only if it corrects a "clerical or typographical" error that would have been clearly evident to one of skill in the art based on the intrinsic evidence, namely the patent and its prosecution history. In order to invalidate a certificate of correction for impermissible broadening of claims, therefore, two things must be proven: "(1) the corrected claims are, in fact, broader than the original claims, and (2) the presence of the clerical or typographical error, or how to correct that error, is not clearly evidence to one of skill in the art." Here, the court had no difficulty finding the claims had been broadened, as while the range simply shifted lower, the corrected claims cover compositions that were not covered by the original claims.

The court also had little trouble finding that the second requirement was met as well. There are three types of mistakes that can be found in a patent:

  1. Mistakes that are immediately apparent and leave no doubt as to what the mistake is (such as an obvious misspelling)
  2. Typographical mistakes not apparent to the reader at all (such as when one word is substituted for another word and both read logically in context)
  3. Mistakes where it is apparent a mistake was made, but not apparent what the mistake is

Only the first category of mistakes is correctable via certificate of correction if a claim would broadened. Here, the mistake fell into the second category, as both "osmolarity" and "osmolality" are spelled correctly and make sense in context. See, for example, a portion of figure 5 below:

Figure 5

Here, as in the claim, mOsmol could equally logically indicate osmolarity or osmolality, and thus no error is apparent to the reader. Because the certificate of correction broadened the claims and the error was not apparent to one of skill in the art, the certificate was invalid. All was not lost for the CAPS, however, as it could still pursue its infringement case based on the original, uncorrected claims.

To read the full decision in Cent. Admixture Pharm. Servs., Inc. v. Adv. Cardiac Solutions, P.C., click here.

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