Citation Network of Section 230 of the Communications Decency Act: A Validated Corpus of Published Federal Circuit Appellate Holdings, 1997–2025

This deposit provides the data and code for a computational legal study of Section 230 of the Communications Decency Act (47 U.S.C. § 230). It includes a validated corpus of 63 published federal circuit and Supreme Court opinions that substantively applied § 230 immunity doctrine between 1997 and 2025, the citation network constructed from those opinions (63 nodes, 320 directed edges, confirmed directed acyclic graph), all derived network metrics, and the complete analysis pipeline. The corpus was constructed by retrieving 211 candidate opinions from CourtListener (courtlistener.com) and subjecting each to systematic human review against a documented operative inclusion criterion and a ten-pattern exclusion taxonomy. The false positive rate in automated retrieval was 70.1% ((211 − 63) / 211 = 148 / 211), a methodological finding with implications for corpus construction in empirical legal studies. Corpus recall was 1.0 (95% Wilson CI: 0.942–1.000) based on a stratified sample of 20 cases across five temporal strata. Key findings: Citation authority concentrates in Zeran v. America Online, Inc., 129 F.3d 327 (4th Cir. 1997), which holds PageRank 0.200 (α = 0.85), accounting for 20.0% of total network authority and ranking first in every annual snapshot from 1997 through 2025. The Leiden algorithm identifies 7 communities (mean NMI stability = 0.621 across 100 seeds, SD = 0.121). Mean pairwise Jensen-Shannon divergence between circuits is 0.660 bits (base 2; range 0.471–0.851), increasing from 0.519 bits in 2003 to 0.660 bits in 2025 with no convergence event. Mutual information between community membership and immunity outcome is 0.155 bits (NMI = 0.119, permutation test p = 0.023, n = 10,000 permutations, seed 42). Platform win rate declined from 80% (2000–2004, n=5) to 38% (2020–2024, n=16), consistent with increasing judicial skepticism toward broad immunity claims. DAG hierarchical level correlates with PageRank at Spearman ρ = −0.838 among cases with at least one inbound citation (n=41, p < 0.0001); full corpus ρ = −0.964 is inflated by 22 dangling nodes sharing identical PageRank floor values. Fair Housing Council v. Roommates.com, LLC, 521 F.3d 1157 (9th Cir. 2008), holds the highest betweenness centrality in the corpus (BC = 0.021) while ranking fifth by PageRank (PR = 0.043), reflecting its structural role as a doctrinal bridge between early immunity expansion cases and later platform-liability litigation. All data and code are provided to support full reproduction of all analyses. See ZENODO_README.md for the complete file inventory and replication_guide.md for step-by-step reproduction instructions.