Andersen Corporation owns a number of patents relating to composite materials made from a mixture of polymer and wood fiber, and to structural parts made from those composite materials. Fiber Composites, LLC, manufactures and sells deck railing and spindle products (the “Fiberon products”), which are made from a polymer and wood fiber mixture.

The parties have classified the six asserted patents into two groups. The four Group I patents cover compositions capable of being extruded into structural members. The two Group II patents cover the extruded structural members themselves. Both parties agree that the disputed claim terms—“composite composition” for the Group I patents and “composite structural member” for the Group II patents—have the same meaning throughout each respective group.

The Fiberon products are made by direct extrusion, a process in which polymer and wood fibers are mixed and melted in an extruder and then forced through a die to form a finished structural part. Fiber contends that its products do not infringe any of the asserted patents because the “composite compositions” of the Group I patents are limited to compositions in either pellet or linear extrudate form, and because the “composite structural members” of the Group II patents are limited to members that are extruded from composites that have previously been extruded into either pellet or linear extrudate form.

After a hearing, the district court agreed with Fiber that the “composite compositions” claimed in the Group I patents are limited to materials that have been extruded to make pellets or the linear extrudate from which pellets can be cut. The court agreed with Andersen, however, that the “composite structural members” claimed in the Group II patents constitute any articles that are made from a composite polymer and wood fiber mixture and have load-bearing capabilities. The court rejected Fiber’s contention that “composite structural members” are limited to items made from a composite mixture that has previously been extruded into pellet or linear extrudate form.

Fiber skipped on the Group I patents by claim construction. A jury found Fiber infringing Group II patents, and awarded $46,200 in damages. The district court denied a requested permanent injunction.

Both parties appealed claim construction: Anderson over Group I non-infringement; Fiber over Group II infringement.

The appeals court agreed with the district court on the Group I claim construction, which was based upon specifications and prosecution histories.

Group II, for 5,486,533 & 5,539,027, was a different story. The issue was whether the process for making the product was to be read into the claim term "composite structural member" for Group II claims. Making a call on the specification, the CAFC figured, would be a toss-up, but the prosecution history was telling.

Fiber urged the district court to construe the term “composite structural member” consistently with the term “composite composition” in the Group I patent claims, to mean an extrudate made from a composite composition that is first formed into a solid pellet or a linear extrudate from which the pellet can be made, and is then re-extruded to form the member. The district court disagreed. The court concluded that the Group II patents are limited to a product, not a product made by a particular process, and that the specification and prosecution history of the Group II patents do not limit the claims in the manner urged by Fiber. Accordingly, the court construed the term “composite structural member” as “a polymer and wood article having load bearing capacity, which can be obtained through a direct extrusion process or made from a composite material without a particular form.”

As the district court correctly noted, the Group II claims do not contain an explicit process-based limitation. We therefore look to the specification and the prosecution history of the Group II patents to determine whether the claim language should be construed as containing any such limitation, as Fiber contends.

Andersen contends, and the district court ruled, that the specification describes a preferred embodiment of the materials used to make the structural members, not an essential step in the manufacture of the structural members claimed in the Group II inventions.

It is generally true, as Andersen argues, that product claims are not limited to the methods of manufacture disclosed in the specification and that “[t]he method of manufacture, even when cited as advantageous, does not of itself convert product claims into claims limited to a particular process. . . . A novel product that meets the criteria of patentability is not limited to the process by which it was made.” Vanguard Prods. Corp. v. Parker Hannifin Corp., 234 F.3d 1370, 1372-73 (Fed. Cir. 2000). However, process steps can be treated as part of a product claim if the patentee has made clear that the process steps are an essential part of the claimed invention.

The specification, however, uses language of requirement, not preference, when it states that the manufacture of the composition and pellet of the invention “requires two important steps,” one of which is the pelletizing step. And the specification attributes the “superior properties of the structural members” largely to “the nature of the pellet set forth [in a table listing ‘pelletizer results’].”

It is true that we have warned against importing limitations from the specification into the claims absent a clear disclaimer of claim scope. See Gillette Co. v. Energizer Holdings, Inc., 405 F.3d 1367, 1375 (Fed. Cir. 2005). We have also recognized the difficulty faced by district courts in trying to walk that tightrope. See Phillips, 415 F.3d at 1323 (“the distinction between using the specification to interpret the meaning of a claim and importing limitations from the specification into the claim can be a difficult one to apply in practice”). Here, if the only intrinsic evidence of restriction were derived from the specification, the issue of claim construction would be a close one because the common specification of the Group II patents does not define and limit the invention as explicitly as does the specification of the Group I patents. However, we conclude that the prosecution history of the Group II patents definitively resolves the question with a clear disavowal and confirms the role of pelletization in the production of the claimed structural members.

During the prosecution of the application that ultimately led to the issuance of the two Group II patents, the examiner rejected claims akin to the Group II claims based on several prior art references. In response to the examiner’s citation of a method patent to Miani, the applicants agued that the composite of Miani is “directly extruded and kept hot during the entire operation. Post extrusion milling is also required to obtain a final useful shape. This type of composite is not the composite taught in the present invention.” In contrast, the applicants stated, “the presently claimed composite is prepared by mixing the melted polymer and wood pulp, forming pelletized material, cooled, then extruded. This affords a smooth structural member without any evidence of polyvinyl chloride degradation.”

That statement clearly identifies “the presently claimed composite,” i.e., the composite that is used to make the claimed structural members, as being prepared through a process that includes “forming pelletized material.” By distinguishing Miani in that manner, the applicants clearly disclaimed structural members made through a direct extrusion process. See N. Am. Container v. Plastipak Packaging, Inc., 415 F.3d 1335, 1345 (Fed. Cir. 2005) (to overcome an obviousness rejection, applicant distinguished his invention based on prior art disclosing “slightly concave” inner walls; the “inescapable consequence of such an argument is that the scope of applicant’s claims cannot cover inner walls that are ‘slightly concave’”); Seachange Int’l, Inc. v. C-Cor Inc., 413 F.3d 1361, 1373 (Fed. Cir. 2005) (“Where an applicant argues that a claim possesses a feature that the prior art does not possess in order to overcome a prior art rejection, the argument may serve to narrow the scope of otherwise broad claim language.”); Rheox, Inc. v. Entact, Inc., 276 F.3d 1319, 1325 (Fed. Cir. 2002) (“Explicit arguments made during prosecution to overcome prior art can lead to narrow claim interpretations . . . .”). The prosecution history thus provides strong support for Fiber’s argument that the Group II patent claims should be narrowly construed as limited to products made by the process described in the specification, rather than covering all composite structural members, regardless of the process by which they were produced.

The CAFC cut little slack for any prosecution disclaimer.

An applicant’s invocation of multiple grounds for distinguishing a prior art reference does not immunize each of them from being used to construe the claim language. Rather, as we have made clear, an applicant’s argument that a prior art reference is distinguishable on a particular ground can serve as a disclaimer of claim scope even if the applicant distinguishes the reference on other grounds as well. See Digital Biometrics, Inc. v. Identix, Inc., 149 F.3d 1335, 1347 (Fed. Cir. 1998) (“While it is true that the applicants went on to specifically distinguish each claim, or group of claims . . . from [the prior art reference] on more narrow grounds, that does not eliminate global comments made to distinguish the applicants’ ‘claimed invention’ from the prior art.”); Gentry Gallery, Inc. v. Berkline Corp., 134 F.3d 1473, 1477 n.* (Fed. Cir. 1998) (when applicant distinguishes a reference on multiple grounds, “any of those grounds may indicate the proper construction of particular claim terms”).

Being part of a family also figured into appeals court reasoning.

A further reason for construing the Group II patents narrowly is that the two groups of patents trace their origins to closely parallel applications filed on the same day in 1992... While it is, of course, possible for applications that begin life as siblings to follow different courses as a result of later events such as amendments and disclaimers, there is no evidence of any such events in this instance that would suggest giving the two sets of claims a strikingly different scope.

Remanded for Group II infringement reappraisal.