Final answer:
The Supreme Court case of Wyoming v. Houghton narrowed the Fourth Amendment protections by allowing the search of passengers' personal possessions in a vehicle given probable cause without the need for a separate warrant.
Step-by-step explanation:
In the case of Wyoming v. Houghton (1999), the Court narrowed the protections under the Fourth Amendment when it held that police who have probable cause to search a vehicle may also search the personal possessions of the passengers.
This ruling is situated within the broader context of the Fourth Amendment, which secures the people from unreasonable searches and seizures and states that no warrants shall issue except upon probable cause, supported by an oath or affirmation, and specifically describing the place to be searched, and the persons or things to be seized.
However, laws and court rulings, like those from the Supreme Court, have established various situations in which a warrant is not necessary for a search or seizure. For instance, there is no general need for a warrant to search the passenger compartment of a car or to search people entering the United States. These rulings are based on exceptions to the warrant requirement, such as when individuals have a diminished expectation of privacy, there is consent, exigent circumstances, or when items are in plain view.