When someone applies for a patent for an invention, the examiner has to consider among other things whether the invention is new and whether it involves an inventive step. In deciding whether or not the invention is new, the examiner has to form a view as to precisely what monopoly the applicant is claiming. That requires him to interpret (or as lawyers say "construe") the applicant's specification.
In Ranbaxy UK Ltd v Warner-Lambert Company  EWHC 2142 (Patents) (12 Oct 2005) Mr Justice Pumfrey gave some guidance as to how patent specifications are to be construed. The case is quite a complex one and much of the judgment is relevant only to the particular facts of that case but the judge did say a few things of general interest. One of these concerned the construction of specifications and passage that is most relevant to the public is as follows:
"I conclude that it is now clear that in deciding what the person skilled in the art would have understood the patentee to be using the language of the claim to mean, the court must approach the problem from the standpoint that the language chosen will be usually of critical importance. An over-meticulous analysis is one that is too willing to draw from a detailed analysis of the grammar, the punctuation and the particular words and phrases used inferences as to meaning that the words might support but which the skilled person would not draw, and it is the antithesis of giving to the words chosen in their context the meaning that the skilled person would give them. Carefulness is not to be equated with over-meticulousness."
What I think that means is that a judge or patent examiner has to put him or herself in the position of someone who could make use of the invention ("a skilled addressee") and give words and phrases the meaning that such skilled addressee would give them. It should not usually look for ingenious meanings that can be drawn from the language unless a more straightforward common sense meaning just won't work.
The judge also dealt with two other issues of general interest. The first was whether our patent examiners and courts consider the question whether an invention is obvious differently from the way that the European Patent Office approaches the question. He didn't think they did. The second issue was whether statements made by an applicant or his patent agent to the British or other Patent Office during the application process ought to be considered when construing a specification. The judge said they shouldn't. This last point is quite significant because the American courts do look at what was said to patent examiners during the application process and will not allow a patentee to say something different from what he or she said during the application process.
I have written a short note about the case in our other blog if anyone is interested in reading more.