What is the current state of the law on the basis of factual findings on a suppression motion?

Prior to 1975, Rule 12 contained no such requirements. Therefore, cases before that date held that factual findings were not mandatory, though we sometimes noted their importance or remanded for factual findings. For example, in United States v. Heimforth, 493 F.2d 970 (9th Cir.), cert. denied, 416 U.S. 908, 94 S.Ct. 1615, 40 L.Ed.2d 113 (1974), we held that while factual findings were not required on every suppression motion, trial courts ought to make them when the issue was a "delicate" one such as voluntariness of consent to a search. Id. at 972. The only means of ensuring that trial courts performed the weighing required by a "totality of circumstances" test was to require explicit factual findings on the issue. Id. See also United States v. Miner, 484 F.2d 1075, 1077 (9th Cir.1973) (factual findings not universally required, but case remanded for further factual findings).