## Facts

- Mangosoft, Inc. and Mangosoft Corporation (collectively, Mangosoft) owned a U.S. patent directed to computer networks that provide a shared virtual-memory system across multiple computers.
- The patent described a distributed architecture in which computers on a network contribute portions of their own persistent storage (such as hard disks) to form a shared, addressable virtual memory space.
- Mangosoft sued Oracle Corporation in the United States District Court for the District of New Hampshire, alleging Oracle infringed the patent.
- During claim construction, the parties disputed the meaning of the phrase in claim 1 requiring “a local persistent memory device” coupled to each computer.
- Mangosoft argued that “local” described the memory device’s association with a particular computer’s contribution to the shared virtual memory space and did not require a specific physical connection method.
- Oracle argued for a narrower meaning, asserting that “local” required the device to be directly attached to a computer (without an intervening communications channel), relying on a technical-dictionary definition of “local device.”
- The district court construed “local” to mean “a computer device (e.g., a hard drive) that is directly attached to a single computer’s processor by, for example, the computer’s bus,” reasoning that Mangosoft’s broader reading would make “local” meaningless.
- Based on that construction, the district court entered judgment of noninfringement for Oracle.
- Mangosoft appealed, challenging the “directly attached” aspect of the construction and arguing the district court effectively imported a dictionary limitation not supported by the patent’s intrinsic record.

## Issues

1. Whether the district court erred by construing “local persistent memory device” to require a memory device that is directly attached to a single computer’s processor (for example, through the computer’s bus).
2. Whether the judgment of noninfringement, which depended on that construction, could stand.

## Decision

- The Federal Circuit reversed the district court’s claim construction to the extent it required “local” to mean “directly attached” to the computer’s processor.
- The Federal Circuit vacated the judgment of noninfringement.
- The case was remanded for further proceedings under the corrected claim construction.

## Legal Principles

- Claim construction begins with the intrinsic evidence (claim language, specification, and prosecution history); extrinsic sources such as dictionaries may assist but cannot override the intrinsic record.
- Courts may not add hardware-connection limits to claim terms unless the patent clearly defines the term that way or clearly disclaims other meanings.
- Avoiding redundancy among claim words is a valid interpretive aim, but it does not justify inserting a narrowing requirement that lacks support in the intrinsic evidence.
- In the context of a distributed system patent, a term like “local” can denote association with a particular computer (or node) in the network, not necessarily a particular physical attachment topology.

## Conclusion

Mangosoft, Inc. v. Oracle Corp. holds that the term “local persistent memory device” could not be narrowed to require a device “directly attached” to a computer’s processor when the patent’s claims and specification did not compel that limit. Because the district court’s noninfringement judgment rested on that improper construction, the Federal Circuit vacated the judgment and remanded for further proceedings using the corrected understanding of “local.”


Mangosoft, Inc. v. Oracle Corp., 525 F.3d 1327 (2008)