In United States v. Newton, 369 F.3d 659, 669-72 (2d Cir. 2004), the Second Circuit Court of Appeals noted some confusion in its precedent regarding how the question of whether a suspect was "free to leave," the seizure test under United States v. Mendenhall, interacted with the issue of custody.
A free-to-leave inquiry reveals only whether the person questioned was seized.
Because seizure is a necessary prerequisite to Miranda, however, it makes sense for a court to begin any custody analysis by asking whether a reasonable person would have thought he was free to leave the police encounter at issue.
If the answer is yes, the Miranda inquiry is at an end; the challenged interrogation did not require advice of rights.
On the other hand, if a reasonable person would not have thought himself free to leave, additional analysis is required because . . . not every seizure constitutes custody for purposes of Miranda.
In such cases, a court must ask whether, in addition to not feeling free to leave, a reasonable person would have understood his freedom of action to have been curtailed to a degree associated with formal arrest.
Only if the answer to this second question is yes was the person "'in custody' for practical purposes," and "entitled to the full panoply of protections prescribed by Miranda." Newton, 369 F.3d at 672 (quoting Berkemer v. McCarty, 468 U.S. 420, 440, 104 S. Ct. 3138, 82 L. Ed. 2d 317 (1984)).