Judge Ronald Whyte of the U.S. District Court for Northern California stayed the coordinated patent infringement cases brought by Rambus because of a conflicting ruling last month from a district court in Delaware about whether or not the patents are enforceable, according to court documents posted online.
The stay extends to other litigation by Rambus against DRAM makers Micron Technology, Samsung Electronics, Hynix Semiconductor and Nanya Technology. Millions of dollars in licensing fees are at stake in the ruling, and cover patents that go into common DRAM technology found in nearly all computers produced today.
Whyte wrote that the stay would remain in place until an appeal to the Delaware court's decision had been ruled upon or by a further order from his court.
Rambus' stock tanked in reaction to the court decision in after-market trading, falling 22.4 percent to US$6.95 by the end of the session.
"While we are disappointed with the stay of the coordinated cases, it is our expectation that the conflicting opinions of the district courts regarding document spoliation will go up together on appeal," said Tom Lavelle, senior vice president and general counsel at Rambus, in a statement.
Micron issued a statement saying it was pleased with the stay order.
The conflicting decisions in the case come from an earlier decision by Judge Whyte in California and the Delaware decision.
In the earlier California case, DRAM maker Hynix had argued that Rambus' patents were unenforceable because the chip designer had destroyed documents related to the case, therefore it's hands were unclean in the situation. That case was argued in the district court for Northern California, and Whyte had ruled that Hynix failed to establish spoliation, therefore the patents could be enforced.
The Delaware case pitted another DRAM maker, Micron, against Rambus. In that case, Judge Sue Robinson of the U.S. District Court for the District of Delaware ruled that Rambus had destroyed innumerable documents relating to all aspects of its business, rendering the 12 DRAM-related patents claimed by Rambus unenforceable.
(Grant Gross in Washington contributed to this report)