This case reads a little like it was written by a teacher who is getting impatient after having tried to explain the same concept thirty times. For whatever reason, trial courts screw this one up A LOT.
Anyway, someone known to the victims as "Rabbit" tried to strangle a couple of people at a park in Boulder. Responding officers aired a description of Rabbit, who had left the area with someone named Bo. Shortly afterwards, three plainclothes officers spotted a couple guys who matched the suspect description.
One of the officers called out "Hey Rabbit," and then Rabbit approached him in a friendly manner and tried to hug him. The officers identified themselves and instructed Rabbit to sit down. While they were waiting for the victim to arrive for a show-up, they asked Rabbit (whose real name is Begay) why someone might have reported that he was involved in a strangulation.
Begay claimed that Bo had been attacked and that he had intervened. Bo denied that any altercation had happened. And then the victimes identified Begay as their attacker. He was subsequently arrested for assault. He moved to suppress his statements, since he had not been read his Miranda rights at the time that he made them.
The trial court suppressed Begay's admission that he had been involved in an altercation, and the people filed an interlocutory appeal. The reasoning the trial court used was that Begay would not have felt free to leave, and that if he had tried to leave then the police would have stopped him. Both of these lines of reasoning are incorrect.
What the officers would have done if Begay tried to leave is irrelevant, unless the officers told him what they would have done. Custody for Miranda purposes is an objective question, so the subjective intent of the officers doesn't matter. What matters is what they actually said and did.
The other mistake the trial court made is a really common one, though. The trial court applied Fourth Amendment reasoning to a Fifth Amendment question.
The Miranda warning requirement is designed to protect a suspect's Fifth Amendment right against self incrimination. Whenever a suspect is subjected to custodial interrogation, the police are required to warn him of his rights. Everyone agrees that Begay was being interrogated (the police were asking questions to elicit incriminating information). The question is whether or not he was in custody at the time.
The trial court held that because he would not have felt free to leave (or otherwise terminate the encounter), he was in custody. But it doesn't matter whether or not Begay would have believed that he was free to go; that's only important in determining whether or not someone is seized for Fourth Amendment purposes. Miranda custody is determined by asking whether or not someone's freedom has been interfered with to the degree associated with formal arrest. In this case, it had not. Begay had been instructed to sit down, but he had not been searched, had not been handcuffed, had not been told he was under arrest, was not in a police dominated atmosphere, the police were speaking to him in friendly tones, he had only been detained for a few minutes, he wasn't taken to a different place by the police... the list goes on. Although Begay was seized for Fourth Amendment purposes (he was clearly being detained), none of that says "under arrest." He was not in custody for Miranda purposes.
The Supreme Court reversed the suppression order.