Patent Law Practice Center

Collateral Estoppel Prevents Reexam Claim from being Enforced

On November 19, 2014, the United States Court of Appeals for the Federal Circuit issued a decision in e.Digital Corporation v. Futurewei Technologies, Inc. e.Digital appealed from a judgment of non-infringement made by the U.S. Federal District Court for the Southern District of California. The district court based its determination of non-infringement on the fact that e.Digital was collaterally estopped from seeking a construction of a claim limitation in e.Digital’s U.S. Patent Nos. 5,491,774 and 5,839,108 different from another court’s previous construction of the same limitation in the ’774 patent.

The Federal Circuit, with Judge Moore writing and joined by Judges O’Malley and Reyna, held that the district court correctly applied collateral estoppel to the ’774 patent, but improperly applied the doctrine to the unrelated ’108 patent.

To understand the ruling in this case one must first look at the prior case that construed the critical claim. Previously, in a litigation in the United States Federal District Court for the District of Colorado, e.Digital asserted claims 1 and 19 of the ’774 patent. The ’774 patent discloses a device with a microphone and a removable, interchangeable flash memory recording medium that allows for audio recording and playback. Asserted claims 1 and 19 recited “a flash memory module which operates as sole memory of the received processed sound electrical signals.” The district court construed the sole memory limitation to require “that the device use only flash memory, not RAM or any other memory system” to store the “received processed sound electrical signals.” The district court based its construction on the written description of the ’774 patent and its determination that the use of RAM had been disclaimed during prosecution. With this claim construction decided, the parties stipulated to a dismissal of the case with prejudice.

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