This flow chart will walk you through the analysis for analyzing the validity of a confession, or any statement made to police by a criminal suspect.
Any involuntary confession is invalid and inadmissible, regardless of whether the suspect has received Miranda warnings. Voluntariness is determined by the totality of the circumstances. Therefore, the first step in analyzing the validity of a confession, or the admissibility of a statement made to police, is to analyze whether or not it is voluntary.
If the statement is voluntary, then you need to determine whether the suspect was given proper Miranda admonitions before the suspect made the statement. Miranda warnings are only required if there is a custodial interrogation. One is in custody if a reasonable person in the same position would not feel free to leave. Interrogation is defined as words or actions the police should know are likely to elicit an incriminating response.
In sum, if there is NO custodial interrogation (and the confession is voluntary), it is valid and admissible. If there is a custodial interrogation and no Miranda warning is given (or if the confession is involuntary), the confession is inadmissible.