A correction is typically required when there is an error in the description, claims or drawings of a European Patent application. If there is suitable basis for the correct wording elsewhere in the specification, it may be preferable to request the change as an amendment in order to avoid the high bar that the EPO places on correction requests. The benefit of a correction request is that the application is treated as if it had always included the corrected text (i.e. from its initial filing date).
When is a correction allowable?
As established in EPO case law, there is a two-step test for determining whether a correction is allowable. The first step is that it must be obvious that an error is present in the document. It is determined whether the incorrect information would be objectively recognisable as incorrect by the person skilled in the art using their common general knowledge. In this sense, external common general knowledge of the field may be used to identify the initial error.
The second step of the test is that the correction of the error must be obvious in the sense that it is immediately evident that nothing else would have been intended than what is offered as the correction. Many correction requests fall down at this step of the test. In particular if there are multiple options as to how to correct the error, it may be difficult to meet this test. For example, if one part of the specification requires a compound to be present in between 0 to 1% by weight and a second part of the specification recites that the compound is present in 2.5% by weight, there is obviously an error so the first test is met. However, it is not necessarily immediately evident what the correction is. The specification could be corrected by altering the range or by altering the point value. Therefore, it is not immediately evident that nothing else would have been intended and the second test may not be met. However, the second test is still carried out in the eyes of the skilled person and hence if there are multiple theoretical corrections, but one or more of these can be technically ruled out or would be immediately rejected by the person skilled in the art, the second test can still be met.