Shire v. Watson: Don’t Double-Down On “Consisting of”
Last month, the Federal Circuit issued its opinion in Shire Development v. Watson Pharmaceuticals, finding that Watson’s generic version of LIALDA® did not infringe U.S. patent 6,773,720 (“the ‘720 patent”). In particular, the Federal Circuit found that no infringement existed because Watson’s product did not satisfy the ‘720 claim limitation requiring the presence of “an inner lipophilic matrix consisting of substances selected from the group consisting of … [specific identified materials].”
At first blush, the Federal Circuit’s decision could be read as interpreting Markush groups in an overly-narrow manner owing to the presence of “consisting of.” Such narrow interpretation of Markush groups, if a general rule, would be troublesome given that these groups are commonly used in chemical practice in the U.S.
However, the Federal Circuit interpreted the ‘720 claims in an extremely narrow manner and found no infringement because “consisting of” was used twice in the lipophilic matrix element.
By way of background, a Markush group is a group which “lists alternative species or elements that can be selected as part of the claimed invention.” It typically contains language such as: “selected from the group consisting of A, B, C and D.”
In finding no infringement, the Federal Circuit stated that using “consisting of” in a claim element creates a very strong presumption that that claim element is “closed” and therefore excludes any elements, steps, or ingredients not specified in the claim and that overcoming this presumption requires the specification and prosecution history to unmistakably manifest an alternative meaning. The Federal Circuit found that the ‘720 claims were “closed” such that the lipophilic matrix could not contain surfactants. Because the lipophilic matrix in Watson’s product contained surfactants, no infringement existed.
In trying to overcome the presumption that the lipophilic matrix element was closed, Shire argued that the ‘720 claims could not be interpreted to exclude the examples in the patent (which contained surfactants sodium starch glycolate and magnesium stearate). In response to this argument, the Federal Circuit stated that “[a]ssuming that Shire is correct about the content of the examples, we still find that Shire has not ‘overcome the exceptionally strong presumption’ that Markush groups are closed…. Shire does not challenge the district court’s construction of ‘consisting of,’ and neither the ’720 patent specification nor the prosecution history reflect intent to adopt a meaning of ‘consisting of’ other than the well-established, limited definition. Thus, we apply the plain claim language.”
Was this correct? Should the claims have been interpreted so narrowly that the examples in the ‘720 patent were excluded?
I went back and looked at the file history for the ‘720 patent (even though it was not really discussed in the opinion). After doing this, I thought this case actually appears to be more clear cut than the Federal Circuit decision indicates. Here is what I found.
The original claim was directed to compositions comprising (a) an inner lipophilic matrix “consisting of” substances ….
In an Office Action, the USPTO noted that the ‘720 specification disclosed the use of surfactants such as sodium starch glycolate and magnesium stearate, and that the phrase “substances” in the claims did not exclude surfactants (despite the use of the phrase “consisting of”). So, at this point, the claims were interpreted as covering compositions in which the inner lipophilic matrix could contain surfactants.
The claims were subsequently amended to add the Markush group (and, thus, the second “consisting of” in the lipophilic matrix element). After the amendment, the claims were directed to compositions comprising (a) an inner lipophilic matrix consisting of substances selected from the group consisting of … [specific identified materials not including surfactants]. Thus, the amendment narrowed the claim scope from compositions containing a matrix which could contain surfactants to compositions containing a matrix which could not contain surfactants.
So it seems to be pretty straightforward from the ‘720 file history.
And the ‘720 claims themselves support this conclusion. There were no dependent claims or optional claim elements identifying other materials that could be in the lipophilic matrix. There was no “comprising” term associated with the lipophilic matrix. The claim language used to describe the lipophilic matrix was limited and narrow.
In the words of the Federal Circuit, “neither the ’720 patent specification nor the prosecution history reflect intent to adopt a meaning of ‘consisting of’ other than the well-established, limited definition.”
The cautionary note here, of course, is to avoid using “consisting of” twice in the same claim element.