Clarity and conciseness of claims (Section 25(5)(b))


5.61 The following defects can arise in the use of ranges in a claim:

(1) 0% to X% of a constituent

A claim must include all of the essential features of an invention and define an operative arrangement. A lower limit of 0% means that the ingredient may or may not be present. Thus, a range comprising 0% should not be permitted if the element is essential to the invention, or if the claim would encompass an inoperative composition of matter for the purpose taught.

Further, in the case of a composition, a claim must define a minimum of two ingredients, at least broadly. If two ingredients are recited, but one of them is defined with a lower limit of 0%, then only one ingredient is properly defined by the claim (see sub-section vi of Section I in this Chapter).

(2) Components do not add up to 100%

5.62 In a composition claim comprising ranges (by weight, by volume,  etc…), the sum ofthe lower and/or upper bounds of the ranges for the components must be able to be combined to reach 100%.

(3) Ranges not specifically disclosed

5.63 When an application includes claims containing a specific limitation with respect to operating conditions, which limitation falls within a broader range disclosed, no  objection should be made to the narrow claim solely on the grounds that it is notspecifically shown in the description, or that the description does not indicate the significance of the disclosed range.

5.64 For example, an application may disclose a process carried out within certain temperature limits, say between 1000°C and 1500°C. No objection should be made if some claims are directed to the process carried out between 1000°C and 1500°C and others to the process carried out at a temperature falling within a smaller range within the disclosed range; say between 1200°C and 1300°C. However, should the broader claims fall in view of prior art, the narrower claims would also fall unless it can be shown that by restricting the process to the narrower range, a new and unobvious result is obtained, e.g. a selection invention (see sub-section viii of Section I in Chapter 4).

5.65 In Auchincloss and another v Agricultural & Veterinary Supplies Ltd. and Others, [1997] RPC 649, a departure from stated range is not considered to be a variant in the Catnic sense; i.e., the applicant is held to the “literal meaning” of their stated range. This was in the case of a claim to a biocidal composition comprising a formulation of a number of ingredients in varying amounts, where each of the ingredients was stated to be used in amounts within the specified ranges.

5.66 However, Aldous L.J. in Lubrizol Corp. v. Esso Petroleum Co. Ltd [1998] RPC 727 at [748] held that a claim to “at least 1.3 succinic groups” include 1.28 or 1.29 succinic groups. In other words, the claim was not construed as a claim to at least 1.30 succinic groups but to 1.3 rounded. Similarly, Pumfrey J in Halliburton Energy Services Inc v Smith International (North Sea) Ltd, [2006] RPC 2, construed a claim to “between 31% and 35% of the total axial force” to mean the number is specified to two significant figures, so including 30.5% to 35.4%, or 30.50% to 35.49%, or 30.500% to 35.499%.

5.67 Therefore, the Examiner has to consider how the skilled person would construe a claimed range in the case under examination. This was summarized by Mr David Young QC (sitting as Deputy judge) in Goldschmidt v EOC Belgium [2000] EWHC Patents 175 at [91] and [92] as follows:

“The evidence is that pH is generally measured by a pH meter and in an industrial plant to one decimal point. The pH values for each of the Examples in the patent are also recorded to one decimal point. This is to be contrasted with the claimed pH range of from 5 to 8.

I consider that one skilled in the art when viewing a pH range of 5 to 8 would not have read such figures as being 5.0 to 8.0 but would have understood them to be to one significant figure only … It is also consistent with comparative Example A4 having a pH of 8.6. In other words when construed purposively, the lower limit pH of 5 is to avoid corrosion problems caused by a pH of below 4.5 and the upper pH limit of 8 is to avoid solidification above a pH of 8.5.”

5.68 Consequently, if the Examiner considers the claimed range to be unclear to the skilled person, a clarity objection should be raised.