UPC Court of Appeal confirms strict approach to correcting patent errors by interpretation

Court of Appeal decision

The Court of Appeal also held that the patent was not sufficiently certain to be valid but disagreed with the Local Division’s construction of the relevant claim. 

Its key ruling was that a linguistic error, spelling mistake or other inaccuracy in a patent claim can only be corrected by way of interpretation if both the existence of the error and the precise way to correct the error are sufficiently certain to the average skilled person at the time of filing, on the basis of the patent claim, taking into account the description and drawings and using common general knowledge. This is a strict standard, because disregarding erroneous parts of claims leads to legal uncertainty for third parties. 

In its view, Alexion’s experts did not give any evidence that the skilled person would be alerted to check for a signal peptide or analyze it in the first place. It was therefore not an obvious error, and the skilled person would interpret the claims as needing the complete sequence, including the 22 amino acids comprising the signal peptide. Furthermore, there were alternative production methods not reliant on signal peptides at all and the patent did not make it clear which approach to pursue. It was also not sufficiently certain to the average skilled person that the error should be corrected by deleting exactly 22 amino acids.

Accordingly, the existence of an error and the precise way to correct it were not sufficiently certain to the average skilled person at the priority date. The applicant’s assertions during the grant proceedings, and the TBA’s endorsement thereof, were an indication of the view of the person skilled in the art at the filing date. 

Based on this claim interpretation, the Court of Appeal found the subject matter of the claim to likely be insufficiently disclosed pursuant to Art. 83 EPC. The Court of Appeal therefore dismissed Alexion's appeal, agreeing with the Local Division that the patent's validity was not sufficiently certain to justify provisional measures. Alexion was ordered to pay the costs of the appeal.

Main Takeaways from the decisions 

1. The standard for correcting errors in the patent claim by way of claim interpretation is strict to reduce legal uncertainty. 
2. There needs to be an “obvious” error and a sufficient degree of certainty for the skilled person to both recognize and correct the error. 
3. Statements made during patent grant proceedings can be relevant to the view of the skilled person when assessing the claim errors during infringement proceedings.
4. This is another reason why precision in patent drafting and prosecution matters because errors may have consequences for patent enforcement.