Not Calling The Inventor As A Witness; And The Effect Of Sequential Unmasking When Instructing An Expert

• Published date: 11 July 2022
• Subject Matter: Intellectual Property, Patent
• Law Firm: Marks & Clerk
• Author: Mr Gregor Grant

The recent case of Advanced Bionics v Med-El considered some issues on obviousness and evidence. The subject matter was cochlear implants. These devices can alleviate severe hearing loss by direct electrical stimulation of the auditory nerve. They have two main components - an external processor which contains a microphone, chips and coil to transmit signal, and an internal implant which receives the signal and operates by directly stimulating the neural tissue within the ear. The resultant impulses are recognised by the brain as sounds. The implant incorporates various components including a magnet. Exposing the patient to the huge magnetic field of an MRI scanner would be a major hazard; the implant could be dislodged, and the presence of the magnet could distort the data. Various strategies had been employed to avoid this problem including using only low field strength MRI scanners, and even surgical removal (and subsequent replacement) of the implant, none of which was optimal. No such problem arises with the external component, which is removable.

An obviousness attack was based on a single item of art, a patent which had been published seven years before the 2010 priority date of the patent in suit. The prior art disclosed the use of a magnet in the implant which could rotate in response to a strong external magnetic field such as that produced by an MRI scanner. The patent in suit claimed a refinement of the rotatable magnet disclosed in the prior art; in particular, it claimed a magnet which was magnetised diametrically, as opposed to the prior magnets which had a magnetic dipole disposed axially. The obviousness argument centred on whether this was inventive over the prior art.

The inventor of that prior patent was the same person as the inventor of the patent in suit. That person was not called as a witness by the patentee (Med-El) and the alleged infringer (AB) sought to make much of this fact. They said that silence from the inventor should raise an inference that he had relevant testimony which was not being revealed. There is a general principle that it is unjust for a party to have to defend itself against what might be termed a "calculated silence". In order to raise an adverse inference from silence it would be necessary to show some evidence about what material evidence the absent person might have provided. The judge held that the inventor might indeed have had been able to provide some relevant input, but so...