Reads the leaf certificate's expiry date from the handshake. An expired certificate blocks the entire site behind an interstitial, and because renewal is usually automated, the failure mode is silent right up until it is total.
Impact is importance multiplied by the confidence tier’s weight — SPECIFICATION 1.0, RESEARCH 0.7, EMERGING 0.3, EXPERIMENTAL 0.1. Two rules backed by the same class of evidence therefore always carry the same weight, which is what makes the score reproducible rather than hand-tuned.