(a) Pleading. A party who intends to raise an issue concerning the law of a state, territory, or other jurisdiction of the United States, or a foreign country shall give notice in the party’s pleadings in accordance with rule 9(k).

(b) United States Jurisdiction. The law of a state, territory, or other jurisdiction of the United States shall be determined as provided in RCW 5.24.

(c) Other Jurisdictions. The court, in determining the law of any jurisdiction other than a state, territory, or other jurisdiction of the United States, may consider any relevant written material or other source, including testimony, having due regard for their trustworthiness, whether or not submitted by a party and whether or not admissible under the Rules of Evidence. If the court considers any material or source not received in open court, prior to its determination the court shall:

(1) Identify in the record such material or source;

(2) Summarize in the record any unwritten information received; and

(3) Afford the parties an opportunity to respond thereto. The court’s determination shall be treated as a ruling on a question of law.