Mitsubishi Electric Corporation and Sisvel International v Oppo and Xiaomi

26 April 2021

Adrian Speck QC and Michael Conway acted for the claimants, Mitsubishi and Sisvel, and Andrew Lykiardopoulos QC acted for the defendants, with Isabel Jamal also acting for the Xiaomi defendants, in this patent infringement trial.

The action concerned a patent for a method and system of improving packet switched voice transmissions or transmission of other real time packet switched services.  The patentee, Sisvel, asserted that the patent was essential to the LTE/4G standard, either directly or by equivalence, and on this basis it was said to be infringed by the defendants.  The defendants denied LTE essentiality, and also ran squeeze arguments to the effect that if the patent was essential to LTE then it was invalid over a number of items of prior art.

Mellor J held that the LTE specification fell outside the scope of the claims on the basis of normal construction and rejected the equivalence case.

Sisvel had applied unconditionally to amend the specification and claims of the patent to exclude a key embodiment from the scope of the claims.  Mellor J held that the proposed amendment would not achieve this aim because far more wording would be required in the claims themselves to do so.

Mellor J held that the proposed amendment did not affect his findings on essentiality or infringement.  The infringement claim failed and the patent was found not to be essential to the LTE standard.

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