Some examples are:
- the "automobile exception,
- search incident to arrest,
- inventory searches,
- hot pursuit,
- stop and frisk,
- border searches,
- plain view,
- school searches,
- seizure of package pending issuance of a warrant,
- consent searches; and
- administrative searches.
There are a number of situations which will justify a warrantless entry or search. Among the most common is where obtaining a warrant would result in the loss or destruction of evidence.
However, in Missouri v. McNeely, the Supreme Court refused to recognize this as a blanket exception to the warrant requirement in DUI cases where police seize a suspect's blood sample without consent.
Who has to prove that immediate and serious consequences would have occurred if the cops attempted to get a warrant? Since 1984, the law has been unchanged . . .
"The police bear a heavy burden when attempting to demonstrate an urgent need that might justify warrantless searches or arrests." Welsh v. Wisconsin, 466 U.S. 740, 749-750, 104 S. Ct. 2091, 80 L. Ed. 2d 732 (1984).