Three months after being accused by Transmeta of patent infringement, Intel struck back, alleging the maker of the Caruso processor is infringing more than a half-dozen of Intel's own patents and alleging the lawsuit is barred by a host of legal defenses.

Intel accuses Transmeta of infringing seven Intel patents relating to microprocessor technology.

In October, Transmeta fired the opening salvo, alleging that Intel's Core 2 Duo, Core and Pentium processors infringed 11 Transmeta patents.

Intel attorneys have invoked the doctrine of unclean hands in their counterblast. They say it applies to Transmeta and invalidates its infringement claims. Other defenses allege Transmeta's patents were obtained through "inequitable conduct" because inventors withheld material information during the application process.

Transmeta said it would not comment until it was able to review the details of Intel's response. ®

• Chips are down for Transmeta (18 November 2008)
• Angry investor offers to buy Transmeta (1 February 2008)
• Intel pays $250m to end Transmeta patent fight (25 October 2007)
• AMD blasts $7.5m right into Transmeta (6 July 2007)
• Transmeta declares war on employment (2 April 2007)
• Transmeta streamlines 75 staff out the door (6 February 2007)
• Intel next target as Opti sues Apple over CPUs? (19 January 2007)
• Transmeta clocks another CEO (16 January 2007)
• Transmeta accuses Intel of patent infringement (12 October 2006)
• Is that a VMware CTO and Transmeta CEO at your start-up? (25 August 2006)
• Transmeta begins second year working for Sony (10 April 2006)