Chabad.org — English translation + Rashi
Torah Temimah points to Horayos 4b (unit 3; single primary locus per emergency Core plan).
E-Daf.com — Horayos 4b
HebrewBooks / Shas PDF
English: A Sanhedrin that has an unfit member is not a Sanhedrin.
Valid Sanhedrin required — a Sanhedrin that includes an unfit member does not generate communal chatas liability.
Any disqualification among the judges voids the status of the Sanhedrin for the purpose of the communal bull. An unfit member renders the entire court incapable of producing the formal hora’ah that the verse contemplates. Only a fully valid Sanhedrin can create the liability.