They say that the most durable lessons you learn are the ones you learn the hard way. As someone who has been writing appellate briefs for some 20 years, I’ve learned many lessons the hard way—from my own mistakes. But some of the best lessons I have learned are from the mistakes my adversaries have made and continue to make. In this article, I distill the 10 most common mistakes that I see in the appellate briefs I read every day.

Some of these mistakes may seem obvious, but based on my observation, they are all too common.