Rambus has been rapped by a US judge for destroying documents related to its lawsuit against Micron. The judge has ruled that, as a result of its misconduct, Rambus cannot enforce twelve patents against Micron.

Whether or not Rambus can enforce the patents against anyone else is a question yet to be decided. Next week Micron and Samsung will be seeking to overturn ten of Rambus' patents.

Judge Sue Robinson of the US District Court of Wilmington, Delaware said there was a 'clear and convincing' showing of bad faith by Rambus and called Rambus' conduct 'obstructive at best, misleading at worst'.

Judge Robinson ruled that Rambus' patent suit against Micron Technology is "unenforceable' by reason of 'spoilation' which means the 'destruction or alteration of evidence'.

The judge's written opinion says that spoliation occurs when a litigant 'intentionally or negligently breached its duty to preserve potentially discoverable evidence'.

Rambus' lawyer, Tom Lavelle, said: "This opinion is highly inconsistent with the findings of the Court in the Northern District of California which looked at the same conduct and found there was nothing improper with our document retention practices."

Following the ruling, Rambus shares fell by 39 per cent. They are currently at $11.24.

See also: Mannerisms, the blog of David Manners. Updated twice daily, it's the distinctive, entertaining, authoritative and never dull commentary on the semiconductor industry, from someone who knows. Sign up for the Mannerisms eNewsletter.

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