In deciding whether to admit hearsay statements made by conspirators against their co-conspirators, what is the test for admitting such statements?

In deciding whether to admit hearsay statements made by conspirators against their co-conspirators "* * we think that the better doctrine is that the judge is always to decide, as concededly he generally must, any issues of fact on which the competence of evidence depends, and that, if he decides it to be competent, he is to leave it to the jury to use like any other evidence, without instructing them to consider it as proof only after they too have decided a preliminary issue which alone makes it competent." United States v. Dennis, 183 F.2d 201, 231 (2 Cir. 1950), aff'd on other grounds, 341 U.S. 494, 71 S.Ct. 857, 95 L.Ed. 1137 (1951). The reason for the rule is there stated: "It is difficult to see what value the declarations could have as proof of the conspiracy, if before using them the jury had to be satisfied that the declarant and the accused were engaged in the conspiracy charged; for upon that hypothesis the declarations would merely serve to confirm what the jury had already decided." 183 F.2d at 230-231.