Colo. R. Crim. P. 26.1
As amended through Rule Change 2024(9), effective May 2, 2024
A party who intends to raise an issue concerning the law of a foreign country shall give reasonable written notice. The court, in determining foreign law, may consider any relevant material or source, including testimony, whether or not submitted by a party. The court's determination shall be treated as a ruling on a question of law.
Colo. R. Crim. P. 26.1
Annotation Am. Jur.2d. See 29 Am. Jur.2d, Evidence, §§ 109, 110.