670.8(b)

(b) Answering and Reply Briefs. Not more than 30 days after service of the appellant's brief, each respondent or opposing party shall file nine copies of the answering brief with proof of service of two copies upon each of the other parties. Not more than 10 days after service of respondent's brief, the appellant may file nine copies of a reply brief with proof of service of two copies upon each of the other parties. If one copy of the appellant's brief was served, only one copy of answering and reply briefs need be served.