What is the test for determining whether a confession is voluntary or involuntary?

"A statement is involuntary if it is not the product of `"a rational intellect and free will."' [Citation.] The test for determining whether a confession is voluntary is whether the defendant's `will was overborne at the time he confessed.' [Citation.] `"The question posed by the due process clause in cases of claimed psychological coercion is whether the influence brought to bear upon the accused were `such as to overbear petitioner's will to resist and bring about confessions not freely self-determined.' [Citation.]" [Citation.] In determining whether or not an accused's will was overborne, "an examination must be made of `all the surrounding circumstancesboth the characteristics of the accused and the details of the interrogation.' [Citation.]" [Citation.]' [Citation.]" (People v. Maury (2003) 30 Cal.4th 342, 404.)

"Police trickery that occurs in the process of a criminal interrogation does not, by itself, render a confession involuntary and violate the state or federal due process clause. [Citation.] Why? Because subterfuge is not necessarily coercive in nature. [Citation.] And unless the police engage in conduct which coerces a suspect into confessing, no finding of involuntariness can be made. [Citations.] [] So long as a police officer's misrepresentations or omissions are not of a kind likely to produce a false confession, confessions prompted by deception are admissible in evidence. [Citations.] Police officers are thus at liberty to utilize deceptive stratagems to trick a guilty person into confessing. The cases from California and federal courts validating such tactics are legion." (People v. Chutan (1999) 72 Cal.App.4th 1276, 1280.)