Colo. R. App. P. 31 (2026)

(a) Time to Serve and File Briefs. The appellant must serve and file the opening brief within 42 days after the record is filed. The appellee must serve and file the answer brief within 35 days after service of the opening brief. The appellant may serve and file a reply brief within 21 days after service of the answer brief. In cases involving cross-appeals the appellant must serve and file the opening brief within 42 days after the record is filed, the cross-appellant’s opening-answer brief and the appellant’s answer-reply brief shall be served and filed within 35 days after service of the opposing party’s brief. The cross-appellant may serve and file a reply brief within 21 days after service of the appellant’s answer-reply brief.

(b) Consequence of Failure to File. If an appellant or cross-appellant fails to file a brief within the time provided by this rule, or within an extended time as permitted by the court, the court may dismiss the appeal on its own motion or a motion to dismiss filed by the appellee or cross-appellee.

Source: (a) amended March 17, 1994, effective July 1, 1994; (b) and (c) amended May 12, 1994, effective July 1, 1994; (a) amended and adopted December 14, 2011, effective January 1, 2012, for all cases pending on or filed on or after January 1, 2012, pursuant to C.R.C.P. 1(b); (a) and (b) amended and (c) repealed and effective June 25, 2015.