RPX data on the Federal Circuit show that infringement is the most common issue appealed from district court patent cases, appearing in over 450 appeals. Claim construction and invalidity (under Sections 102/103/112) are the next two most frequent issues, each of which appears in over 300 appeals. Two other key issues round out the top five: damages/fees/costs (appearing in around 275 appeals) and invalidity under Alice/Section 101 (just over 240 appeals).
The data further reveal that these top issues vary significantly by affirmance rate. While the Federal Circuit affirms about half of the time for infringement, claim construction, and 102/103/112 invalidity, damages have a 40% affirmance rate. Moreover, patent eligibility rulings withstand Federal Circuit scrutiny to the greatest extent of the top Federal Circuit issues by appeal, at 64% affirmance.