Parameters At The EPO - Issues Concerning Clarity And Sufficiency

Parameters are generally used in patent claims to define subject matter which cannot be expressed in terms of structural features.  They are often relied upon for inventions in the chemical field, but can in fact be used in any technical area.  Parameters can relate to features that can be measured directly, such as the density or melting point of a substance; measured indirectly, such as the tacticity of a polymer; or that can be calculated, such as the superficial velocity of a flow in a reactor.  They can also be expressed in terms of relationships between such features.

Some interesting themes have developed from the decisions of the EPO's Technical Boards of Appeal for parameter cases, in particular in relation to the assessment of clarity and sufficiency. These are reflected in the Guidelines for Examination in the European Patent Office, Part F, Chapter IV, 4.11, which indicate that when inventions are characterised by parameters, it is necessary that "those