In what circumstances will the federal constitutional rule of automatic reversal apply in cases involving coerced confessions?

In People v. Stroble (1951) 36 Cal.2d 615, 226 P.2d 330, by contrast, we concluded that the federal constitutional rule of automatic reversal did not apply on the peculiar facts of that case--erroneously, it turns out. In affirming a judgment of death therein, we "assume[d]" that the first of at least six confessions made by the defendant was coerced. (Id. at p. 623, 226 P.2d 330.) We then recognized that the "introduction in evidence of such a confession ... would offend the due process clause of the Fourteenth Amendment" and require automatic reversal. (Ibid.) Nevertheless, we held that, under the circumstances presented, the "use of the first confession could not have affected the fairness of defendant's trial, because defendant thereafter made at least five confessions, of materially similar substance and unquestioned admissibility, which were put in evidence." (Ibid.)