In what circumstances can a confession be used in a criminal case?

In Sassounian, while we acknowledged that, in some cases, a confession can provide the prosecution with an "`evidentiary bombshell which shatters the defense,'" its effect in a given case depends on whether a jury would have found it believable. (In re Sassounian, supra, 9 Cal.4th at p. 548, 37 Cal.Rptr.2d 446, 887 P.2d 527; quoting People v. Schader (1965) 62 Cal.2d 716, 731, 44 Cal.Rptr. 193, 401 P.2d 665.) Because the Sassounian informant had been extensively impeached at trial, we believed it was "open to question" whether the jury found the confession believable. (In re Sassounian, supra, 9 Cal.4th at p. 548, 37 Cal.Rptr.2d 446, 887 P.2d 527.) We therefore applied the reasonable probability test and determined that had the confession not been introduced, the result would have been the same. We concluded that there was no reasonable probability that admission of the confession could have affected the outcome because "[s]eparate and apart from the [confession] there was overwhelming evidence" supporting the conviction. (In re Sassounian, supra, 9 Cal.4th at p. 548, 37 Cal.Rptr.2d 446, 887 P.2d 527.) We proceed to the same analysis here.