There are some court recognized exceptions to the warrant requirements for searches. Consent, plain view, search incident to arrest, exigent circumstances, hot pursuit, impending destruction of evidence, etc... Articulation is part of police training. If the officer can articulate a reasonable and legal reason for the actions he takes, he/she will probably be justified and upheld in court. If he/she goes on an unjustified power trip or unreasonable fishing expedition there are a host of remedies available to a citizen with a savvy attorney.

Never argue with a cop in uniform on the street. It's like being in the proper lane while having a head on collision with a tractor trailer. Sure, you were right, and maybe your beneficiary will see some cash. Small benefit to you.