According to Patently-O's review of PTAB appeal data from 2009 through 2026, Section 101 patent-eligibility challenges have again grown to about a fifth of all appeals before the Board. That share matches the level seen in 2009, suggesting the issue has returned to a familiar equilibrium after years of fluctuation.
The analysis also finds that the reversal spike—a period when the Board frequently overturned examiner rejections on Section 101 grounds—has faded. In addition, the Board has nearly stopped raising Section 101 on its own initiative, a practice that had drawn criticism from patent owners. The data points to a more restrained, less activist role for the PTAB on eligibility questions.
Because the report is based on a single source, the findings reflect Patently-O's methodology and interpretation. No independent data is available here to confirm the exact figures, but the trend described is consistent across the three metrics noted: appeal share, reversal rate, and sua sponte actions.