Answer: Berkemer v. McCarty was a case that turned on whether or not routine questioning at traffic stop of, does apply. And so on this particular case, it extended Miranda warnings and clarified that it applies to misdemeanor cases. Before that, they were basically saying that Miranda only applied to serious cases, but this particular case clarified and extended the fact that Miranda applies to misdemeanor cases.
However, it does state though, that routine questioning at a traffic stop is not custodial. And so the two takeaways you get from Berkemer is that, one, it does apply to misdemeanor cases, but two, a traffic stop is not custodial when they’re just doing routine questioning and therefore, Miranda is not required for that.
The basic definition of custodial is not free to leave. So basically, any freedom of movement was restrained to an extent associated with a formal arrest.