Marine Polymer Technologies, Inc. v. HemCon, Inc. (Fed. Cir. 2011) is a widely reported case that raises some questions about the scope of the application of intervening rights.  It involves a matter where the literal language of a claim was not amended, yet absolute intervening rights were still found to apply to the accused infringer.  Marine Polymer owns U.S. Pat. No. 6,864,245 (the ’245 patent), which claims a polymer p-GlcNAc that accelerates hemostasis (the process which causes bleeding to stop) and is useful in trauma units for treating serious wounds.  Marine Polymer sued HemCon, alleging that HemCon infringed claims 6, 7, 10, 11, 12, 17, and 20 of the ’245 patent. 

The ‘245 Patent

Independent claim 6 of the ‘245 patent recites:

6.  A biocompatible [p-GlcNAc] comprising up to about 150,000 N-acetylglucosamine monosaccharides covalently attached in a β-1→4 conformation and having a molecular weight of up to about 30 million daltons in which at least one N-acetylglucosamine monosaccharide has been deacetylated. 

Perhaps the most surprising thing about this case is that the only disputed claim term on appeal was “biocompatible.” According to the decision, like claim 6, each of the claims of the ’245 patent requires that the p-GlcNAc be “biocompatible.”  Biocompatibility, as used in the ‘245 patent, refers to the extent to which the p-GlcNAc causes a negative biological reaction when placed in contact with human tissue.  Apparently, the specification disclosed four tests that can be used to determine the biocompatibility of a substance, including an elution test. The elution test involves washing the substance with a solution to create an extract which is then tested on living cells to judge its toxicity.

According to the specification, the elution test yielded a score of zero to four on a biological reactivity scale, with: zero representing no reactivity; one representing slight reactivity; two representing mild reactivity; and three or four representing moderate or severe reactivity. The specification explains that using the elution test, “p-GlcNAc[ ] meets the bio-compatibility test if none of the cultures treated with [p-GlcNAc] show[s] a greater than mild reactivity” (i.e., no more than two on the reactivity scale).  (Col. 42, ll. 42–44.) The specification also explains that p-GlcNAc can be biocompatible using the other three biocompatibility tests even if the polymer exhibits some biological reactivity. The other tests have similar scales for determining reactivity, and all three allow the p-GlcNAc to pass the test even it exhibits some biological reactivity.  (Col. 43, ll. 54–60, col. 44, ll. 25–56, & col. 45, ll. 41–43.)

As originally issued, three of the dependent claims (3, 12, and 20) specifically required an elution test score of zero (i.e., no reactivity under that test).  Six of the original dependent claims (4, 5, 13, 14, 21, and 22) specifically required elution test scores of one or two (i.e., slight or mild reactivity under that test).   The other claims did not include any explicit requirement that the p-GlcNAc meet a specific score on any of the biocompatibility tests.

Markman Order and District Court Judgment

In the resulting Markman proceedings, the district court adopted a construction, concluding that “biocompatible p-GlcNAc” meant p-GlcNAc “polymers . . . with low variability, high purity, and no detectable biological reactivity as determined by biocompatibility tests.” (emphasis added).

Based on its claim construction, the district court granted summary judgment of literal infringement of all seven asserted claims, relying on expert evidence that biocompatibility tests of HemCon’s accused products had shown “no detectable biological reactivity.” A jury trial was held to determine validity and damages. The jury found that the ’245 patent was not anticipated and that Marine Polymer was entitled to a reasonable royalty of approximately 88% of HemCon’s profits.  The district court entered final judgment on September 22, 2010, granting reasonable royalty damages for the past infringement in the amount of $29,410,246.1 On September 16, 2010, it also issued a permanent injunction barring future infringement of the asserted claims of the ’245 patent.

Reexamination of the ‘245 Patent

During the pendency of the district court proceedings, HemCon requested reexamination of the ’245 patent.  The examiner initially adopted a different claim construction than the district court, concluding that “biocompatible” meant “low variability, high purity, and little or no detectable reactivity.” (emphasis added).  In this preliminary rejection, the examiner noted his disagreement with the district court’s claim construction, explaining that the court’s construction was inconsistent with the numerous dependent claims that required a specific elution test score of zero, one, or two.  Based on that construction, he issued a preliminary rejection of all the claims of the ’245 patent as invalid in light of the prior art.  With respect to the “biocompatibility” limitation, he explained that any difference between the claimed biocompatibility and that disclosed by the prior art references is minor and would have been obvious to a person of ordinary skill in the art.

In response, Marine Polymer argued that the district court’s interpretation of the term ‘biocompatible’ should be adopted in the reexamination and therefore “biocompatible” should be construed to mean “no detectable biological reactivity”.  Marine Polymer also cancelled the six original dependent claims that had specifically required an elution test score of one or two (i.e., that required at least some reactivity).  The examiner then approved the claims as amended, noting that upon cancellation of the claims which required elution test scores of 1 or 2, he now agreed with the district court’s definition of the term “biocompatible.”  The PTO confirmed the claims as amended after the district court had entered its final judgment on September 22, 2010.  On March 29, 2011, the PTO issued a reexamination certificate, cancelling dependent claims 4, 5, 13, 14, 21, and 22.

Appeal of District Court Decision to the Federal Circuit

The final judgment was appealed to the Federal Circuit.  The Federal Circuit held that the scope of the claims of ‘245 patent was substantively changed in reexamination, and that HemCon was therefore entitled to absolute intervening rights.  The majority acknowledged that the independent claim was not literally amended, but made its decision based on the narrowed construction of “biocompatible” which was deemed to be a limitation of all of the claims of the ‘245 patent.  The Federal Circuit remanded the case to the district court for further findings concerning whether HemCon was entitled to equitable intervening rights.

The dissent by Judge Lourie is very interesting.  He noted that dependent claims 12 and 20 expressly require that the recited biocompatible “has an elution test score of 0.”  In his opinion, these claims recite biocompatibles that were equivalent in scope to the narrowed construction adopted for the term “biocompatible” in reexamination.  Therefore, in his view claims 12 and 20 are not “amended or new claims.”  Given that, he concludes that HemCon has infringed these claims as originally issued and is not entitled to absolute intervening rights.

In contrast, the majority commented on claims 12 and 20 and found that they were substantively narrowed despite the limitation on the elution test: 

Just as the district court’s construction narrowed the original claims by requiring “no detectable biological reactivity,” it narrowed claims 12 and 20 by defining the term “biocompatible” to require that the p-GlcNAc exhibit no reactivity under any biocompatibility tests that were performed. Adoption of that construction changed the scope of claims 12 and 20 because p-GlcNAc that exhibited some reactivity on one of the other biocompatibility tests (other than the elution test) would no longer fall within the scope of claims 12 and 20. HemCon is entitled to absolute intervening rights as to all claims, including claims 12 and 20.

Therefore, there must be p-GlcNAc variations that have zero reactivity under the elution test, but some reactivity in other tests, else the limitations in 12 and 20 concerning the elution test would be the same as the new construction of “biocompatible” in their respective independent claims.  And if there are p-GlcNAc variations that can have zero reactivity in other tests, yet have larger reactivities via the elution test, the cancellation of the dependent claims was not necessary.  (Editor’s Note:  this may have been addressed in the record, but is not clear to the author who practices in the electrical and software arts.)

Case Raises Questions

This case renews attention to the effect of narrowed construction in reexamination.  Some of the more interesting questions to ponder are:

• Arguably, the substantive nature of the new construction was highlighted by the cancellation of dependent claims, because they were arguably inconsistent with the scope of the narrowed construction.  But what would have happened if the dependent claims were not cancelled (or if they did not have to be cancelled)?  Would the amendment appear as significant/substantive?  Would HemCon be entitled to absolute intervening rights in that case?
• What would have happened if the examiner in reexamination had overlooked the inconsistency between the narrowed construction and the dependent claims that were ultimately cancelled?  Would this appeal have had the same result?
• What would have happened if the reexamination was appealed to the BPAI and the resulting decision occurred after the appeal of the district court decision?
• What would have happened if no reexamination had been conducted?

It will be interesting to see if any other information becomes available on remand.  However, this case continues to get a lot of attention from the reexamination bar.