dissenting.
I respectfully dissent from the decision of the majority to vacate and remand. I would affirm. The district court did a thorough job of analyzing all the aspects of the claim construction of the term “carbonate” and arrived at the correct conclusion. There was no ambiguity and it is clear to *1000me from the record that bicarbonate was not part of the definition of carbonate.
It is very clear that the bicarbonate anion, which contains a hydrogen atom, is not the same as the carbonate anion, which lacks a hydrogen atom. They are different ions. Sodium carbonate even has a different common name (soda ash) from sodium bicarbonate (baking soda). Solutions of the compounds have different pHs (strongly alkaline vs. weakly acidic). See The Merck Index (Maryadele J. O’Neil ed., 13th ed.2001) (stating that the hydrogen atom brings a degree of acidity to what is a more basic compound).
Most importantly, when the patentee, Warner-Lambert (‘WL”), wanted to include both compounds in a patent, it did that expressly. See U.S. Patent 4,425,355, col. 6, II. 51-53 (“a suitable basic reagent, such as ... alkali carbonates or bicarbonates”); U.S. Patent 4,344,949, col. 3, II. 18-20. It thus knew how to distinguish one ion from the other. It is absolutely compelling, beyond anything just stated, that WL intended to include only carbonates in its formulation in this patent because it knew of Merck prior art which, if bicarbonate were included in its patent, might render that patent invalid. Merck’s product in the public domain contained an ACE inhibitor, a saccharide, and a bicarbonate, exactly what would be claimed if Schwarz’s interpretation of the claim here were adopted. That is why we have the unusual situation in which a licensor, the patentee WL, is urging the narrower formulation against the broader interpretation of its licensee.
We have often said that a patentee’s litigation statements do not count for much when a claim is being interpreted. That is because they are self-serving and after-the-fact. See Solomon v. Kimberly-Clark Corp., 216 F.3d 1372, 1379-80 (Fed.Cir.2000). However, when a patentee argues for a narrower interpretation, essentially against its interest, at least in an infringement context, that fact is meaningful.
As for the plural reference to “carbonates” in the patent, that relates to magnesium, calcium, and sodium carbonates, for example, not to bicarbonates.
Thus, with all due respect to my colleagues, I must dissent. The district court arrived at the correct decision and should be affirmed.