CAFC: Prosecution Disclaimer Does Not Preclude Infringement Suit Against Product Exhibiting Disclaimed Element

PatentlyOImage028SanDisk v. Memorex (Fed. Cir. 2005).

SanDisk holds a patent on Flash EEPROM with an improved architecture that extends the useful life of the device. 

When construing the claims, the trial court ruled that the claims did not cover systems with any memory cells grouped into non-partitioned sectors.  Because the accused devices included many sectors of memory cells that included non-partitioned sectors, the lower court granted defendants’ summary judgment motion that the devices did not infringe.

On appeal, the CAFC reviewed claim construction de novo, and reversed. First, the court looked at the plain language of the claim:

A method of operating a computer system including a processor and a memory system, wherein the memory system includes an array of non-volatile floating gate memory cells partitioned into a plurality of sectors that individually include a distinct group of said array of memory cells that are erasable together as a unit . . .

The appellate court found that the “including” transition, which is “a patent law term of art [meaning] ‘comprising.’”

Second, the appellate court rejected the district court’s finding that SanDisk had, during prosecution of the patent, disclaimed any cells grouped into non-partitioned sectors — finding that although the patent had been distinguished based on the partitioning, the disclaimer only applies to elements “subject to the claimed method, and no more.”  Thus, with open claim language, a device may be found to infringe a patent even if the device includes elements that were disclaimed during prosecution.

[T]here is no prior reason why that memory cell array or the discussion of it should be presumed to exhaust every cell on every EEprom in the “memory system” recited in the claim preambles. Given the open language in the claims, there is no reason for the court to read the prosecution argument with such a presumption in mind. Put differently, the reference to “each sector” means “each sector” subject to the claimed method, and no more. In short, SanDisk’s reading of this prosecution argument is at least reasonable. Thus, focusing on this passage alone, there is no “clear and unmistakable surrender” within the meaning of Golight.

Summary Judgment of Noninfringement Vacated and Remanded