Final answer:
In Nevada, an officer needs a warrant to arrest an adult for a misdemeanor unless the officer observes the crime being committed. This is linked to the probable cause requirement and Fourth Amendment protections, with certain exceptions like exigent circumstances and plain view.
Step-by-step explanation:
In the state of Nevada, an officer cannot arrest an adult for a misdemeanor without a warrant, unless he witnesses the person committing it. The enforcement of this law is rooted in the principle of probable cause, which applies to arrest warrants. Unless a police officer personally observes a misdemeanor being committed, they are generally required to obtain a warrant before detaining an individual.
The only exceptions to the warrant requirement occur under certain circumstances, such as when there is a reasonable expectation that evidence may be destroyed before a warrant is issued, if the person consents to a search, or when evidence of a crime is in plain view of a government official. A key aspect of the Fourth Amendment is to protect citizens from unreasonable searches and seizures, ensuring that detentions and arrests without a warrant are made with proper legal justification.