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5.5.4.6 Parametric claims

Date Published

Characteristics

A parametric claim is one that defines a product or feature of a process in terms of its parameters, for example:

'A composition comprising a detergent having an XYZ value of greater than 5.0.'

The style of claiming referred to as ‘parameteritis’ or ‘parametritis’, seeks to repatent the prior art by limiting claims by reference to a series of parameters which were not mentioned in the prior art (Raychem Corp.’s Patents [1998] RPC 31 at page 37).

Sometimes it includes references to a series of parameters measured on test equipment which did not exist at the time of the prior art. It may be impossible to prove the prior art inevitably exhibited the parameters and therefore impossible to prove anticipation. However, to limit a claim by reference to a particular meaningless and arbitrary parameter has nothing to do with patentability. Patents are not given for skill in inventing technically meaningless parameters (Raychem Corp.’s Patents [1998] RPC 31 at pages 46 and 47).

Claim construction

A key consideration when construing parametric claims is whether the parameters have been chosen to achieve a technical effect, or whether they are an arbitrary convenience (Euroceltique S. A. [2009] APO 21 at paragraph 112).

Possible objections

Defining a product or process by its parameters may be appropriate if the product or process cannot be adequately defined by other means. However, the parameters must be clearly and reliably determined, either by objective procedures known in the art or as indicated in the description. Similar considerations apply to a feature of a process that is defined in terms of its parameters.

If a claim defines a new or unusual parameter that is not recognised in the art, a clarity objection may be appropriate.

Novelty considerations

Examiners need to be aware that the use of parameters within a claim may be an attempt to disguise a lack of novelty. Where there is nothing in the specification that suggest that the proportions or ranges used are in any way part of the invention, other than a mere reference to them, it is likely a case of ‘parameteritis’ (Williams Advanced Materials, Inc. v Target Technology Company LLC (2004) FCA 1405). At paragraph 48 Bennett J stated:

“Indeed, there is nothing in the specification that suggests that the proportions or the ranges of metals in the alloys are in any way part of the invention, other than the mere reference to them.  It is a case of ‘parameteritis’.”

However, claims with certain parameters can be novel if the patent specification and supporting evidence indicate that the parameters have been carefully chosen, are part of the invention, and are related to a claimed advantage (Austal Ships Pty Ltd v Stena Rederi Aktiebolag (2005) FCA 805). In this case Bennett J stated at paragraph 108:

"Unlike in Williams Advanced Materials, Inc. v Target Technology Company LLC [2004] FCA 1405 at [48], there is reference in the patent specification and evidence which supports the fact that the parameters have been carefully chosen, are part of the invention and are related to a claimed advantage as part of the combination of the design."


Amended Reasons

Amended Reason Date Amended

Published for testing
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