Although Lord Justice Jacob disclaimed any pretension of deciding any question of legal principle, the CA's decision in Corus UK Ltd. v Qual-Chem Ltd.  EWCA Civ 1177 is still worth reading because it assists an understanding of art 123 (2) of the EPC post European Central Bank v Document Security Systems Inc.  EWCA Civ 192 (19 March 2008) and Vector Corporation v Glatt Air Techniques Inc.  EWCA Civ 805 (19 Oct 2007) and also on the construction of claims post Kirin-Amgen. The judgment is also mercifully short largely because the lords justices did not regurgitate the facts found by His Honour Judge Fysh QC at first instance (Qual-Chem Ltd. v Corus UK Ltd. EWPCC 1 (7 Feb 2008)).
Art 123 EPC provides for amendment of European patents:
"(1) The European patent application or European patent may be amended in proceedings before the European Patent Office, in accordance with the Implementing Regulations. In any event, the applicant shall be given at least one opportunity to amend the application of his own volition.
(2) The European patent application or European patent may not be amended in such a way that it contains subject-matter which extends beyond the content of the application as filed.
(3) The European patent may not be amended in such a way as to extend the protection it confers."
The point arose because the defendant had argued that the amended patent was invalid in that its specification described the treatment of slag as well as molten iron in the smelting process whereas the original specification focused on the treatment of molten iron alone. Referring to his judgment in Richardson-Vicks Patent  RPC 568 at 576 that "the test of added matter is whether a skilled man would, upon looking at the amended specification, learn anything about the invention which he could not learn from the unamended specification", Lord Justice Jacob said at para. :
"So what we have to do is to ascertain what is disclosed explicitly and implicitly in the "A" specification. This must be done without hindsight, i.e. without knowing the result being sought. The same exercise must be performed on the "C" specification. We are looking to see whether there is an extension of subject matter."
Applying that rule his lordship analysed the original specification and found that it clearly disclosed the use of the process for the treatment of slag alone.
The point there was whether the words "being tailored" in the context of
"the conveying gas pressure being tailored with respect to the conveyed additive material to cause the conveyed additive material to penetrate into and remain in the slag"
meant that once all the other variables (nature and thickness of slag, nature and shape of additive and so on had been selected) the pressure had to be adjusted or "tailored" so that additive was conveyed into and remained in the slag. If that was right the patent could be infringed only if the infringing apparatus had some pressure adjustment means. Lord Justice Jacob dealt with that by looking at the purpose of the method which is to get additive into slag. A purposive construction, see, pure pre-Kirin, pre-Improver even, Catnic. The specification has to be read in the way that the woman skilled in the art would read it and in that context mindful of the purpose she would read the word "tailored “as meaning "so arrived at" or "chosen".
Throwing in the Kitchen Sink
At trial Michael Fysh had to deal with no less than 10 discrete points or sub-points. As Uncle Robin put it with his characteristic bluntness at para.  "The taking of many points is often the mark of a party which does not feel it has a single 'killer'." Oh dear, we've all done that haven't we - particularly before the CPR imposed cost penalties on unnecessary point taking. The only thing I would say to that is that Johnson v. Gore Wood & Co.  UKHL 65,  2 AC 1,  1 All ER 481,  2 WLR 72 forces us to take every point because we don't get a second bite of the cherry.