How have courts interpreted the "plain view" doctrine in the US?

The American authority quoted was Coolidge v. New Hampshire, 403 U.S. 443 (1971), at p. 466: What the “plain view” cases have in common is that the police officer in each of them had a prior justification for an intrusion in the course of which he came inadvertently across a piece of evidence incriminating the accused. The doctrine serves to supplement the prior justification—whether it be a warrant for another object, hot pursuit, search incident to lawful arrest, or some other legitimate reason for being present unconnected with a search directed against the accused—and permits the warrantless seizure.