What is a plain view search?

The phrase is slightly misleading, since the doctrine describes a seizure rather than a search.

Three requirements. The officer has to be lawfully present where the observation is made. The item has to be in plain view — no moving things, no opening containers. And its incriminating character has to be immediately apparent, meaning without further examination.

Each requirement does work. If the officer wasn't lawfully there, plain view doesn't apply. If he had to shift an object to see what it was, that's a search. And if the item's illegality wasn't apparent without inspection, the doctrine doesn't cover it.

That third element is where Florida's cannabis situation intersects. When a substance could equally be legal hemp or illegal marijuana, whether its incriminating nature is "immediately apparent" becomes a genuine question — and it's part of what the appellate courts have been working through.