“Where a patent specification made a technical effect “plausible” it was open to a party to mount a challenge to the existence of that effect by the use of later evidence. There was no principled objection to the admission of evidence as to the true nature of the advance made by the invention in connection with an objection of lack of inventive step.”
WLR Daily, 29th July 2013
Source: www.iclr.co.uk
