As many people are aware, the U.S. Constitution imposes limits on the power of law enforcement to search property. A police officer requires a warrant or probable cause in order to conduct a search. However, sometimes an officer might claim a rationale to search a car or a home because something incriminating lay in plain view.
When a police officer conducts a search of a vehicle based upon observing a possibly illegal or incriminating item through a car window, an officer is justifying a search according to the plain view doctrine. The Cornell Law School provides some background on this doctrine and how police officers may or may not utilize it.
Objects in plain view
To permit an officer to search a location where an object is in view, the object should have an obvious incriminating character. The officer must have probable cause to believe that the object has some connection to criminal activity. If there is genuine doubt about the item as an illegal or incriminating object, a court will likely rule the search unconstitutional.
Objects in containers
Another area where a plain view doctrine may not justify a search is when an object is inside a container. If something possibly incriminating sits inside a solid container like a thermos, an officer would probably need a warrant to seize it. The officer could not observe the object since the object lay inside the thermos, so a judge may not approve of the search under the plain view doctrine.
Context is important
While ordinary objects can serve as part of criminal activity, context is important if an officer is to have justification for a plain view search. For instance, people can use common lawful objects as drug paraphernalia. But for an officer to consider an object as paraphernalia, the officer would have to locate the object near a set of drugs or some incriminating item to confirm its illegal use in order to provide justification for a plain view search.