SanDisk's Claim of Patent Infringement Reinstated

12 December 2005

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.

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.

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