Corresponding structures for Means-Plus-Function claims must be more than Prior art references listed in the patent – the structures must be expressly disclosed in the specification - Pressure Products Medical Supplies v. Greatbatch (Fed. Cir. Mar. 24, 2010)

Pressure Products Medical Supplies v. Greatbatch (Fed. Cir. Mar. 24, 2010)
The Federal Circuit overruled a district court’s claim construction,  vacated the district court’s finding of infringement and remanded for further proceedings in light of the correct claim construction.  The trial court erroneously used structures from the prior art references listed in the patent to provide a definition for “score lines”  encompassing structures not disclosed expressly in the patent specification.
US 5312355 http://www.google.com/patents?vid=USPAT5312355
US 5125904 http://www.google.com/patents/about?id=Y78EAAAAEBAJ&d





A key feature of the 355’ and  904’ patents is that both the Sheath 12 and valve assembly 14 can be split using score lines 36 38.   In the background section,  355’ 904’ patents list references that show methods and structures for only splittable sheaths ( compare with the 355’ 904’ patents both splitable sheath 12 and splitable valve assemblies 14).
 
This case involves the trial court’s definition of a claim 1 Mean-plus-function term “means for permitting removal of said hemostatic valve and introducer sheath..”  and the claim 4 definition of “score line”.
Claims 1 and 4  from  the US  5125904 asserted patent: (Bold added)
1. An sheath assembly for use with a lead or catheter comprising:
an introducer sheath;
a hemostatic valve coupled to said introducer sheath, said hemostatic valve and introducer sheath being arranged and configured to permit introduction of at least one lead or catheter therethrough;
means for permitting removal of said hemostatic valve and introducer sheath from said lead or catheter disposed therethrough without requiring said introducer sheath and hemostatic valve to be removed from an end of said lead or catheter,
whereby said assembly may remain in a vein throughout an operation with the advantage of free lead exchange and easier lead manipulation without substantial bleeding, risk of air embolism, clotting or repeated sheath insertion related trauma from lead exchange.
4. The assembly of claim 1 wherein said means for permitting removal of said hemostatic valve and introducer sheath is a score line defined in said hemostatic valve and introducer sheath along which said hemostatic valve and introducer sheath may be separated.


The Accused devices are introducers include a feature that defendant Enpath calls a “cut” or “slit” that allows the PTFE sheath to be torn apart.

A relevant section of the 904’ patent that provides structure for the means-plus-function element in claim 1 is :

FIG. 3 illustrates in enlarged scale a rear perspective view of introducer sheath assembly 10. According to the invention, both valve assembly 14 and sheath 12 are splittable or have a peel away construction. Again, the detailed nature by which such splittable structure is implemented or how peel-away feature is realized is not critical to the invention. Any method now known or later devised by which such sheaths 12 and valve assemblies 14 may be split or separated may be employed and are contemplated as being within the scope of the invention.

In the illustrated embodiment, sheath 12 and valve assembly 14 are shown as integrally fabricated and having a pair of longitudinal score lines 34 and 36 defined along their axial length. Score lines 34 and 36 are shown as being diametrically opposed from each other across the cross section of introducer sheath 10. Intravenous sidearm 18 is depicted in FIG. 3 as being disposed between score lines 34 and 36 interlying surface between them. Score lines 34 and 36 are shown as having a V-shaped cross section but have such a shape and depth as to permit the entire length of introducer sheath 10 to be manually separated. It is contemplated that at the end of the operation the physician will grasp opposing flange portions 38 and 40 to peel them apart while pulling out the sheath and holding the lead. This will cause valve body 16 to tear along a section line depicted by dotted lines 42 through the body of valve assembly 14. Both body portions 16a and b may be scored to facilitate this tearing. In addition the bonding of the body portions 16a and 16b assists in tearing the inner body portion as the outer body portion is being torn along its corresponding tear line. The portions become through the bonding as a single body and the fracture or tear propagates from the outer body portion through the inner body portion. Membrane 22 has a weak line or score line and can easily be removed from the lead.

904’ patent  (bold added) Col. 5, L 62 to Col. 6, L 25)
The Federal Circuit court stated:  (Bold added)

In the context of the corresponding structure to independent claim 1 of the Lee patents, the trial court erred in expanding the definition of “score line” to include structures not disclosed in the specifications of the Lee patents. Section 112 requires that the corresponding structure must be “described in the specification.”
The Lee patents give a laundry list of prior art references. See ’904 patent col.1 ll.41–61; ’355 patent col.1 ll.45–63. The trial court included the structures disclosed within that list of prior art references as corresponding structures for claim 1 by including them in its definition of “score line.” In doing so, the trial court impermissibly expanded the corresponding structure of claim 1 to include structures not described in the specification.
Trial courts cannot look to the prior art, identified by nothing more than its title and citation in a patent, to provide corresponding structure for a means-plus-function limitation. In this case, these references provide alternatives to scoring. Although many of the disclosed alternatives may well be determined to be structural equivalents permitted by section 112, paragraph 6—a question of fact for the jury—these alternative methods of splitting or peeling cannot be treated as the disclosed structures for the removal means. Simply mentioning prior art references in a patent does not suffice as a specification description to give the patentee outright claim to all of the structures disclosed in those references.
…….

The specification does not expressly describe use of a cut or a slit or a tear for removal. The specification explains, “[t]he score line comprises a pair of lines defined in the hemostatic valve and introducer sheath. The pair of score lines are diametrically opposed from each other on the hemostatic valve and introducer sheath.” ’904 patent col.3 ll.14–18. The patent further explains, “score lines 34 and 36 are shown as having a V-shaped cross section but have such a shape and depth as to permit the entire length of introducer sheath 10 to be manually separated.” Id. col.6 ll.7–10. The specification recognizes a difference between score lines and slots. Id. col.6 ll.28–32 (”However, it is entirely possible that score lines 34 and 36 will be continued through flanges 38 and 40 to provide deep scores instead of open slots 44 and 46.” (emphasis added)).

The court determined a definition for “score lines” using only structures expressly in the specification: (bold added)

The trial court erroneously used structures from the prior art references listed in the patent to provide a definition for score lines encompassing structures not disclosed expressly in the patent specification. As such, this court detects error in the trial court’s definition. Score lines are “one or more lines defined in the hemostatic valve and introducer sheath” as supported by the specification. This court remands for further proceedings in light of the proper construction of the term “score lines.” Those further proceedings will allow appropriate measures to also ascertain the structural equivalents of the express structure in the specification corresponding to the claimed function.

Note that the court will not allow incorporation by reference to include a structure in the prior art for a means-plus-function elements:

In Atmel Corp. v. Info. Storage Devices, Inc., 198 F.3d 1374, 1381 (Fed. Cir. 1999), this court refused to utilize the concept of incorporation by reference to include a structure in the prior art as a corresponding structure for a means-plus-function claim element.

Practice pointers –
If you use means-plus-function claim elements, corresponding structures must be expressly disclosed in the specification. You should not try to incorporate by reference any corresponding structures.
Note in this case the patents do not expressly state the “means for removal” are accomplished by the “scores”.  It may have helped to state many examples of structures that provides the “means for removal”. 
Also, corresponding structures for Means-plus-function claims must be expressly disclosed in the spec. in the 904 patent the broad statement below needed to be backed up by expressly giving examples.

Any method now known or later devised by which such sheaths 12 and valve assemblies 14 may be split or separated may be employed and are contemplated as being within the scope of the invention.

The patentee could have possibly added examples of sheath splitting structures/techniques from the prior art references and expanded the examples to include splitting of both the sheath and valve assembly.
I read about the case on the Gray on Claims blog.