SanDisk’s Claim of Patent Infringement Reinstated

The U.S. Supreme Court on Monday rejected an appeal by digital media manufacturers that are facing a patent infringement lawsuit filed by flash data storage card maker SanDisk Corp.

Background: In October 2001, SanDisk sued four Flash memory system manufacturers: Memorex Products, Inc. (“Memorex”) Pretec Electronics Corp. (“Pretec”) Ritek Corp. (“Ritek”) and Power Quotient International Co., Ltd. Power Quotient International Co. reached an early settlement with SanDisk.

SanDisk sought a preliminary injunction against Memorex, Pretec and Ritek (the defendants). The defendants opposed, and the trial court denied the motion.

District Court’s ruling: In denying the motion, the district court relied primarily on a finding of SanDisk’s disclaimer. The court found, that SanDisk ‘’clearly and unmistakably’’ disclaimed any method or device in which Flash EEprom memory cells were not grouped into partitioned sectors.

With that claim construction the district court granted Ritek summary judgment of non-infringement, because Ritek had presented evidence that their products include some sectors that are not partitioned. Pretec and Memorex moved for summary judgment on the same ground.

As the defendants’ products contained sectors of memory cells lacking such partitions, the district court granted summary judgment that various Flash memory devices made by Pretec and Memorex did not infringe SanDisk’s claims to its ‘Flash EEprom systems’ patent.Â

SanDisk appealed the district court’s judgment of no infringement in favour of Memorex, Pretec, and Ritek.

Federal Appeals Court ruling: SanDisk contended that the district court erred in this conclusion. It argued, nothing in the prosecution history provides a clear and unmistakable disclaimer as found by the district court.

 The federal court agreed with SanDisk and held that, ‘’an ambiguous disclaimer, however, does not advance the patent’s notice function or justify public reliance, and the court will not use it to limit a claim term’s ordinary meaning’’. ‘’There is no “clear and unmistakable” disclaimer if a prosecution argument is subject to more than one reasonable interpretation, one of which is consistent with a proffered meaning of the disputed term.’’

 Vacating the district court’s judgement on the basis of erroneous claim construction, the federal court ruled that SanDisk’s claims were not limited to memory systems in which every memory cell is grouped into a partitioned sector. The federal court remanded the case for further proceedings.

The Supreme Court’s ruling: The Supreme Court today denied Ritek’s and Pretec‘s petition aimed at reversing federal court’s ruling that reinstated SanDisk’s infringement suit. Ritek, Memorex and Pretec now will have to go back full circle to face up to SanDisk’s allegations of patent infringement.