2.4.4.5 Resiling from Acknowledged Prior Art

Date Published

Where acknowledged prior art would render a claim or claims of a specification invalid, mere deletion of that art will, in general, be insufficient to overcome the problem, unless evidence is provided to establish the fact that there was an error. This was discussed in Chapman and Cook, and Lectro Linx Ld v Deltavis Ld (1930) 47 RPC 163 at page 173:

"If a patentee, though entirely erroneously, does state by way of what I may call recital in his specification that a particular form of thing is common and then by some oversight or some mistake claims a monopoly in that particular form of thing he will have, so to speak, recited himself out of Court and I venture to doubt whether he could possibly maintain any claim to a monopoly in a thing which he has recognised to be something which existed."

This approach (which was obiter) was moderated somewhat in Gerber Garment Technology v Lectra Systems [1995] FSR 492, where it was stated:

"In Sonotone Corporation v Multitone Electric Co Ltd (1955) 72 RPC 131, at 140 however, Sir Raymond Evershed M.R., speaking obiter, expressed the view that such a recital constituted an admission which must necessarily carry great weight, but that it did not estop the patentee or debar him from leading evidence to contradict it.

In my judgement this is a correct statement of the law."

See also Mobil Oil Corporation's Application (1975) AOJP 2323 at the paragraph bridging pages 2324 and 2325.

Examiners should note that it is permissible for an applicant to delete a reference to acknowledged prior art from the specification during examination. However, such a deletion may not in itself overcome a novelty objection taken in light of the acknowledged prior art, if that prior art was available before the relevant priority date.