Police to secure a valid waiver

The Supreme Court has held that the Sixth Amendment right to counsel requires police to secure a valid waiver of the right to counsel or see to it that counsel is present at any pre-trial “critical stage” of a criminal prosecution. Referring to the Miranda v. Arizona, 384 U.S. 436 (1966) case, discuss how the Court applied the requirements of the Sixth Amendment right to counsel to custodial interrogation.