Final answer:
An officer is typically required to obtain a search warrant or arrest warrant to enter a home and arrest a visitor, unless an exception to the warrant requirement applies. Exceptions include consent, exigent circumstances, or evidence in plain view. The case of Georgia v. Randolph specifically states that warrantless searches cannot be conducted in a home where one occupant objects, even if another consents.
Step-by-step explanation:
If an officer wants to enter a home where the person to be arrested is merely a visitor and not a resident, a search warrant or arrest warrant is typically required. Probable cause must be established for the issuance of such a warrant by demonstrating to a judge that there is sufficient reason to believe a crime has been committed or evidence can be found. In the landmark case of Georgia v. Randolph, the Supreme Court held that police cannot conduct a warrantless search in a home where one occupant consents and the other objects. However, exceptions to the warrant requirement exist, such as exigent circumstances, consent from the person in control of the property, the plain view doctrine, and situations where a person lacks a "reasonable expectation of privacy". When it comes to vehicles, the courts have found that police do not generally need a warrant to search the passenger compartment of a car (Terry v. Ohio).
Overall, for an officer to enter a residence to arrest a visitor, they must have a warrant unless one of the exceptions to the Fourth Amendment applies. These exceptions include situations such as consent by the resident, evidence in plain view, or exigent circumstances where evidence could be destroyed before a warrant can be obtained. Consent is a key factor that police may rely on; however, as per Georgia v. Randolph, if another occupant objects to the search, the consent is invalid and a warrant is necessary.