Opposition Proceedings Before The EPO – An Overview

Any European patent granted by the European Patent Office (EPO) may be opposed under Article 99 of the European Patent Convention (EPC). If successful, the opposition has the effect of centrally invalidating or limiting the patent in all states in which that patent has effect. As such, understanding the basics of opposition proceedings before the EPO is important for both patent proprietors and opponents alike.

Why file an Opposition?

In comparison to national invalidation proceedings, oppositions before the EPO have three main benefits for opponents.

First, as mentioned above, the outcome of the opposition applies in all countries in which the European patent has been validated, thereby avoiding the need for multiple national invalidation actions. Secondly, in recent years the EPO has prioritized reducing the overall timeline of oppositions, with standard files now having a mean processing time of about 19 months. Finally, the cost of EPO opposition