Rambus ‘918 Patent Healthy Despite Loss at PTO Board

Scott Daniels | January 14, 2011

Despite a suggestion in the blogosphere that Rambus has been “tripped up” in reexamination, its U.S. Patent No. 6,034,918 for a method of operation of a semiconductor device remains commercially strong.  Vigorously litigated patents are often tested on several fronts: in multiple District Courts cases, at the U.S. ITC, in reexamination at the PTO, and ultimately at the Federal Circuit.  To assess a patent’s strength, its status in each forum must be considered. 

On Wednesday, the PTO Board affirmed the reexamination examiner’s rejection of independent claim 18 as being invalid over the prior art.  The examiner had already confirmed the validity, however, of the other two claims in reexamination, dependent claims 24 and 33.  The reexamination had been requested by Hynix whom Rambus had sued for infringement of the ‘918 patent in the Northern District of California.  In that case, Judge Ronald Whyte issued a judgment last March that claims 24 and 33 of the ‘918 patent, along with a number of claims from other Rambus patents, were valid and infringed. Thus, Wednesday’s Board decision, though favorable to Hynix, does not undermine Rambus’ position vis-a-vis Hynix.

Rambus didn’t fare as well in its case against Micron in Delaware.  There, Judge Sue Robinson found that Rambus’ patents, including the ‘918 patent, were unenforceable because Rambus employees had destroyed potentially relevant documents before the start of that litigation.  Hynix had raised the same spoliation defense in the California case, but Judge Whyte rejected it.  

Rambus had also sued a number of importers at the U.S. ITC under Section 337 for infringement of the ‘918 patent.  In that investigation, the Commission determined that the asserted ‘918 claims, claims 1, 2, 4, 7 and 11, were invalid over the prior art.  Accordingly, the Commission’s invalidity determination did not affect the claims found to be infringed in the California action.  But even if the ITC had determined that claims 24 and 33 were invalid, such a determination would not be binding on Rambus in District Court cases in view of legislative history of Section 337. 

The Delaware and California District Court cases are now on appeal at the Federal Circuit where the parties presented oral argument on the spoliation issue in early October.  From listening to that argument, I suspect that the Federal Circuit will side with Rambus by concluding that the “death penalty” of unenforceability was too severe and that a lesser sanction would be appropriate.  The fact that Judge Newman is a member of the panel of judges that heard the argument certainly does not reduce Rambus’ chances of reversing Judge Robinson’s adverse judgment.           

We as reexamination practitioners might expect the Board to have the final say on the issue of patent validity.  Yet here, the fate of the ‘918 patent will be determined by the Federal Circuit, not the PTO.  The message for patentees intending litigation on multiple fronts is to selectively assert different claims in the different forums, as Rambus has done with the ‘918 patent.

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