What is the test for determining whether a confession was coerced?

The Disbrow court concluded, moreover, that "there are compelling reasons to disregard Nudd contained in the ratio decidendi of Miranda." (16 Cal.3d at p. 110, 127 Cal.Rptr. 360, 545 P.2d 272.) It reasoned: "In People v. Fioritto (1968) ... 68 Cal.2d 714, 717 [68 Cal.Rptr. 817, 441 P.2d 625], we said, 'A principal objective of [Miranda ] was to establish safeguards that would liberate courts insofar as possible from the difficult and troublesome necessity of adjudicating in each case whether coercive influences, psychological or physical, had been employed to secure admissions or confessions.' The precision with which the Miranda court established not simply broad procedural guidelines but a precise manual for the conducting of custodial interrogations can be interpreted only as expressing an intention to create a single, uncomplicated, universally applicable test for determining whether a particular confession was coerced. If proper warnings are given voluntariness is assured, at least in the absence of 'traditional' coercion. Conversely, if an accused is inadequately informed of his rights involuntariness is assumed, and the statements are inadmissible at trial.