What standard of review applies to the consent of a witness?

We turn first to the question of what standard of review is applicable to this issue. While no case from our circuit has been called to our attention deciding the precise question, we have decided analogous issues. For example, in United States v. Hart, 546 F.2d 798, 801-02 (9th Cir. 1976) (en banc), cert. denied, sub nom. Robles v. United States, 429 U.S. 1120, 97 S.Ct. 1155, 51 L.Ed.2d 571 (1977), we concluded that the determination that police officers had done everything "reasonably necessary and proper" to make a witness available was factual in nature and our review was by the clearly erroneous standard.

In United States v. Page, 302 F.2d 81, 85 (9th Cir. 1962), we held similarly that whether consent was "freely and intelligently given" and that there was "no duress or coercion, express or implied" was a factual issue to be tested by the clearly erroneous standard. See also, United States v. Lemon, 550 F.2d 467, 472 (9th Cir. 1977), and United States v. Tolias, 548 F.2d 277, 278 (9th Cir. 1977). ²

Our experience dictates that the question of exigent circumstances is fundamentally the same type of issue as the questions of voluntariness of a consent and whether officers had done everything reasonably necessary to produce a witness. Certainly, a finding of exigent circumstances is no less based on the "fact-finding tribunal's experience with the mainsprings of human conduct." Commissioner of Internal Revenue v. Duberstein, 363 U.S. 278, 289, 80 S.Ct. 1190, 1198, 4 L.Ed.2d 1218

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