Excluded Subject Matter (5) - Diagnostic methods

Initially the exclusion of diagnostic methods from patentability may sound extremely broad and difficult to work around. However, this exception has been construed narrowly by the EPO, and Boards of Appeal, and relatively rarely causes difficulties for applicants. 

The first point on which the exception is narrow is that to be excluded a claimed method must include all steps leading to a diagnosis. These steps may be summarised as:

1. Examination/collection of data. 

2.  Comparing data to standard values. 

3. Identifying differences between the standard and collected values. 

4.  Deriving a diagnosis from the differences. 

A claim including all of these steps would be very narrow and it is unusual that all of them are linked in an inventive method such that they have to be included in a claim to properly define the invention.  It is therefore common to be able to omit one or more step and hence avoid the exception, while still capturing the invention to meet the other requirements for patentability. As an example, imaging methods are often patentable, even if they present data against standard values, because they merely provide the tools to derive a diagnosis but do not perform the diagnosis step. 

This marks a major distinction in approach compared to the exclusion of methods of treatment by therapy or surgery. A method claim is excluded from patentability if it comprises or encompasses at least one feature defining a therapeutic or surgical step. However, a much narrower interpretation is applied for diagnostic methods, where all steps leading to a diagnosis must be claimed (or at least implicit). 

A further restriction on the scope of this exception is that the method must be performed on the human or animal body.  This has been construed to require that all relevant technical steps must be performed on the body but typically this requirement applies to the first step.  This means that tests on samples from a body, for example blood tests, avoid the exception (i.e. may be patentable) provided the step of collecting the sample from the body is not claimed.  In practice, this makes the exception very narrow. 

When protecting diagnostic methods, other exclusions to patentability also need to be considered as there is often a close relationship.  For example, the collection of tissue samples may lead to a claim being excluded as a surgical method, or data comparison steps may be challenged as non-technical steps which cannot contribute to an inventive step. 

With careful drafting the diagnostic method exception can often be avoided and diagnostic inventions can usually be protected without significant difficulties caused by the exception.  

This article is a part of our EPO Practice and Peculiarities series. Click here to explore.