What is the test for determining whether a statement obtained by a police constable under the Miranda Act is inadmissible?

On appeal, we defer to the trial court's factual findings which are supported by substantial evidence and independently determine whether the statement was obtained in violation of Miranda. (People v. Nelson (2012) 53 Cal.4th 367, 380.)

"Just as 'The mere fact of ministration of drugs does not establish an impairment of capacity so as to render a confession inadmissible' [citations] so too the mere fact of voluntary consumption of alcohol fails to establish such an impairment." (People v. Hendricks (1987) 43 Cal.3d 584, 591.)