Final answer:
Law enforcement officers can search the passenger compartment of a vehicle during a traffic stop without a warrant if they have probable cause that a crime has been committed. Situations involving vehicles often have exceptions to the warrant requirement due to their mobile nature and the practical challenges of obtaining a warrant promptly.
Step-by-step explanation:
When performing a traffic stop and there is a need to search a vehicle, law enforcement officers often conduct what is known as a search incident to arrest, provided they have probable cause to believe that a crime has been committed. Under the legal framework set by decisions such as Terry v. Ohio, officers may frisk a suspect for weapons if they have reasonable suspicion. In situations where there isn't a reasonable expectation of privacy, such as in vehicles which are readily mobile and subject to regulations, the warrant requirement is often relaxed.
The Fourth Amendment provides protection against unreasonable searches and seizures, but the Supreme Court has recognized exceptions for vehicles, given their mobile nature and the impracticality of obtaining a warrant in a timely manner. The courts allow the search of the passenger compartment without a warrant as long as there is probable cause. It's important to note that the level of evidence needed to obtain a warrant (probable cause) is a lower threshold than what's required to secure a conviction.