We really are experts when it comes to opposing patents and our enviable success rate speaks for itself. Only 10.4% of all patents that we have opposed over the last 10 years have been maintained as granted. That's significantly better than the EPO’s 10-year average of 26.3%.
Our success rate is similarly impressive when we look at the proportion of patents that are completely revoked following an opposition handled by us, with 45.1% of all patents that we have opposed over the last 10 years having been revoked. Again, this is significantly better than the EPO average of 32%.
Opposition stats for IPC A61K (medical preparations, including pharmaceutical compositions)
We decided to take an even closer look and see how the stats changed if we focused on IPC A61K (medical preparations, including pharmaceutical compositions). In this class, 92.3% of all patents we’ve opposed were revoked or amended in some way - so only 7.7% survived unscathed and were maintained as granted following opposition by Mewburn Ellis. Compare this to the EPO average of 22% and you can really see where our expertise makes a difference. Focusing on single opponent oppositions shows that this difference is down to us alone: only 17.1% of A61K patents were maintained as granted where we represented the sole opponent, compared to the EPO average for single opponents of 26.6%.
Our figures are even more impressive when considering A61K (medical preparations, including pharmaceutical compositions) opposition cases that included an appeal stage, where not a single patent that we have opposed in the last 10 years has been maintained as granted following completion of the appeal stage, compared to the EPO’s average of 16.1%. In 55.9% of these cases which went to appeal, the patent was revoked, compared to the EPO average of 43.2%. To see when this unblemished record began, we looked even further back to 2005 (which is as far as IPQuants provides data for). Remarkably, not a single patent in A61K (medical preparations, including pharmaceutical compositions) that Mewburn Ellis has been tasked with opposing has been maintained as granted following completion of the appeal stage in the last 21 years.
Opposition stats for IPC C07 (organic chemistry)
We also looked in more detail at IPC code C07. In this class, 94.2% of all patents that we opposed in the last 10 years have been revoked or amended in some way as well, so similarly to A61K, only 5.8% have been maintained as granted. This is once again much better than the EPO average, where 22.7% of all opposed patents in C07 have been maintained as granted over the last 10 years. Once more, focusing on single opponent oppositions shows that we make the difference: only 14.3% of C07 patents were maintained as granted where we represented the sole opponent, compared to the EPO average for single opponents of 27.8%.
As with A61K, not a single C07 (organic chemistry) patent that we have opposed in the last 10 years has been maintained as granted following completion of an appeal stage, compared to the EPO’s average of 15.9%. In 50% of these cases which went to appeal, the patent was revoked, compared to the EPO average of 41.2%. Like A61K, our unblemished record of not having a patent in C07 (organic chemistry) maintained as granted following completion of an appeal stage where we handled the opposition stretches back at least as far as 2005!
Source: Statistics provided by IpQuants AG. Data correct as of September 2026.*
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